MH370 A NEW STUDY

 

MH370 Flight Path Analysis

Case Study

by Richard Godfrey, Dr. Hannes Coetzee (ZS6BZP) and Prof. Simon Maskell

30th August 2023

At 17:19:26 UTC Malaysian Air Traffic Control (ATC) at the Lumpur Radar station contacted

MH370 with a routine message: “Malaysian Three Seven Zero contact Ho Chi Minh one two zero

decimal niner good night.” Captain Zaharie Shah responded at 17:19:30 UTC: “Good night

Malaysian Three Seven Zero.” At 17:20:36 UTC, just 66 seconds later, the Mode S transponder

symbol of MH370 dropped off the Malaysian ATC radar display. MH370 had gone ‘dark’ and

disappeared into the night sky diverting back over Malaysia to the Malacca Strait according to

primary civilian and military radar data.

This case study examines the use of radio waves from the Weak Signal Propagation Reporter

(WSPR) and the historic database called WSPRnet. WSPR data can be used as a multi-static

passive radar system to detect and track aircraft, where WSPR links between radio transmitters

and receivers align with the aircraft position along a great circle path. Signal level and signal

frequency modulations can result, when an aircraft flight path intersects with the propagation path

of a WSPR link. Together with the Boeing aircraft performance data, the MAS Operations fuel and

engineering data, the weather data enroute, the Inmarsat satellite data and the drift analysis of the

41 items of possible MH370 floating debris that have been recovered from around the Indian

Ocean, a comprehensive picture of the final hours of flight MH370 can be collated.

The purpose of detecting and tracking MH370 across the Indian Ocean is to ensure the reliability

of the flight path analysis during the 7 hours 46 minutes the aircraft was in the air and therefore

the accuracy of the end point position, where MH370 ran out of fuel after 7 hours 35 minutes and

then subsequently crashed around 11 minutes later. The alignment of the WSPR analysis with the

analyses from Boeing, Inmarsat and the drift analysis from the University of Western Australia is a

significant multi-disciplinary outcome, which all point to the same crash area. There have been 41

items of confirmed or possible MH370 floating debris recovered from round the Indian Ocean.

Flight MH370 was diverted to the Indian Ocean, where it crashed after fuel exhaustion on 8th

March 2014 at some point after the last satellite signal was received at 00:19:37 UTC. At the time

of writing of this case study, MH370 still has not been found despite extensive surface and

underwater searches. Around 10 million commercial passengers fly every day and the safety of

the airline industry relies on finding the cause of every aircraft accident.

APPROACH OPERATIONS IN REDUCED VISIBILITY

 

HUD With a Velocity (Flight-Path)

Vector Reduces Lateral Error During

Landing in Restricted Visibility

Örjan Goteman

Scandinavian Airlines

Stockholm, Sweden

Kip Smith and Sidney Dekker

Department of Industrial Ergonomics

Linköping Institute of Technology

The majority of approaches (the segment of flight immediately before touchdown) performed in U.S. and European civil air transport operation are conducted as Category I instrument landing system (ILS) approaches. For a Category I approach the two critical factors when making the decision of whether to

land are the decision height and the RVR. Decision height refers to the aircraft’s vertical distance above the runway threshold where the pilot must make the decision to land or make a go-around. The pilot must be able to see at least some of the approach or runway lights at the decision height. The approach lights will then guide the pilot to the runway.

The RVR is a measure of horizontal visibility defined by the length of visible approach and runway lights in the ambient atmospheric conditions. If the RVR is too low the pilot will not be able to see any of the approach lights at the decision height and must make a go-around.

This RVR is expected to allow the pilot to see a visual segment of the ground that contains enough of the runway approach lights to judge the aircraft’s lateral position, cross-track velocity, and position in roll when the aircraft is at decision height.

EXPERIMENT 1

Method

Forty-eight pilots from a major European airline volunteered to participate. All were qualified to fly the B–737–700 aircraft and had completed their HUD training for the operator. The HUD training sessions consisted of 1 day of theory and two simulator sessions of 4 hr duration each. Experience on the B–737–700 varied from 50 hr to more than 1,000 hr. There is every reason to believe that these participants are representative of the population of commercial pilots to whom regulators need the data to generalize. Apparatus. We used a CAE B–737–700 training simulator with aircraft aerodynamics and visual angles valid for B–737–700 to collect data. This six-axis full-motion simulator is approved for low-visibility operations down to an RVR of 200 m. The simulator’s visual system had a field of vision of 180°/40° with a focal distance greater than 10 m.

The head-down instrumentation was a B–737–700 instrument panel in primary flight display (PFD) configuration with flight director guidance. This instrumentation was available in both the with-HUD and the no-HUD conditions.

The HUD installed in the simulator was a Rockwell-Collins Flight Dynamics HGS–4000® (Head-up Guidance System), certified for low-visibility operations down to and including an RVR of 200 m. The HUD symbology and functionality used in the experiment met the production-line standard specification for the instrument meterological conditions (IMC) mode used when conducting Category I ILS and non-precision approaches (see Figure 6). This mode was deliberately chosen to improve the external validity on the form of operational usability of the study. In normal operations, the vast majority of ILSs are only approved for Category I operations. The HUD provided conformal display of flight path (velocity) and flight-path guidance. The flight path was displayed as a circle with slanted wings. Flight-path guidance was displayed in the form of a ring inside the flight-path symbol. Flight-path guidance was not available in the conventional head-down instrumentation.

The radio navigation facilities simulated in the study conformed to the ICAO (1996) standard for ILS radio navigation aids for Category I approaches transmitting a radio beam for both vertical and lateral reference. The integrity of the transmitted beam is guaranteed to keep the aircraft within allowable airspace, safe from

Gulfstream GVII-G500 in level flight at 40,000 feet, Mach 0.90. 

obstacles down to 200 ft height, corresponding to lowest allowable decision height. Approaches in Experiment 1 were flown to a simulated runway with a system of approach lights 900 m in length. This length falls within the full facilities system category of European aviation regulation (JAA, 2004b).

Procedure. Each pilot manually flew two approaches using standard operating procedures of the airline. The scenarios started as a 6 nm final to the runway in lower than standard or standard RVR in a simulated 10 kt left crosswind. In the with-HUD condition, the pilots kept the aircraft on lateral and vertical by following the flight-path guidance ring with the flight-path symbol on the HUD. At 50 ft above the runway threshold, the guidance cue was automatically removed and the pilots performed the landing flare using external visual cues in conjunction with the HUD flight-path symbol. The HGS–4000® IMC mode incorporating automatic removal of the guidance cue was deliberately chosen to ensure that the pilots could not attend solely to the HUD symbology in the with-HUD conditions.

In the no-HUD condition the pilots kept the aircraft on lateral and vertical track by following the flight director bar guidance. At decision height they continued the approach and landing using the external cues only.

All approaches were recorded to determine approach success. Approach and landing plots for approaches ending with a landing were printed using the aircraft’s center of gravity as the reference to determine the size of the touchdown footprint.

Results

Approach success rate. Each of the 48 pilots attempted two approaches.

Thirty-seven made two successful landings, one with HUD and one without. Three made go-arounds in both conditions. Two pilots landed with the HUD and made go-arounds without the HUD; six landed without the HUD and made go-arounds with the HUD.

The McNemar change test is the appropriate statistical procedure for testing the null hypothesis that pilots were equally likely to (a) land with the HUD and go-around without it, and (b) land without the HUD and go-around with it (Siegel & Castellan, 1988). Because the observed test statistic, calculated from the values given earlier (2 and 6), is 1.125 and is less than the criterion, x² (.05, 1) = 3.84, we cannot reject the null hypothesis. Accordingly we infer that HUD use had no impact on approach success rate.

Touchdown performance. As noted previously, 11 of the 48 pilots conducted one or two go-arounds. The simulator failed to capture the location of the landing footprint for another 7 pilots. As a result the data set for comparing the touchdown footprints across the HUD and no-HUD conditions consists of 30 pairs of approaches. Of these 30, 15 were flown using the HUD in the first approach and 15 using the conventional head-down instruments (no-HUD) in the first approach; 15 were flown in standard RVR (550 m) conditions and 15 in lower than standard RVR conditions (450 m).

Lateral touchdown performance was measured as the absolute lateral deviation from the runway centerline at touchdown. The data for the main effect of HUD use are shown in Figure 7. Landings were closer to the centerline when pilots used the HUD. The two-factors repeated-measures analysis of variance (ANOVA) revealed a strong effect for HUD use on the lateral component of the touchdown footprint, F(1, 28) = 9.05, p < .006,   n² = .12 indicating a power of .80 at α = .05.

The main effects for RVR and order of HUD condition were not significant. There was, however, a marginally significant interaction between HUD use and the order

EXPERIMENT 2

Method

The method, procedure, and design used in the second experiment were identical to those used in the first experiment with the few exceptions discussed here. The different criteria for standard RVR across facility types preclude collapsing and analyzing the data as a single experiment.

Participants. Forty-five pilots from the same major European airline volunteered to participate. None of the volunteers had participated in Experiment 1. All were qualified to fly the B–737–700 aircraft and had completed theirHUDtraining for the operator. Experience on the B–737–700 varied from more than 50 hr to more than 1,000 hr.

Simulated ground facilities. Approaches in Experiment 2 were flown to simulations of a runway with 420mof approach lights. This length falls within the intermediate facilities category of approach lights as defined by European aviation regulations (JAA, 2004b).

 

Results

Approach success rate. Each of the 45 pilots attempted two approaches.

Thirty-two made two successful landings, one with HUD and one without. Four pilots made go-arounds in both conditions. Three pilots landed with the HUD and made go-arounds without the HUD; six pilots landed without the HUD and made go-arounds with the HUD. Once again we used the McNemar change test to test the null hypothesis that pilots were equally likely to (a) land with the HUD and go-around without it, and (b) land without the HUD and go-around with it. Because the observed test statistic, calculated from the values given previously (3 and 6) is 0.44 and is less than the criterion, x² (.05, 1) = 3.84, we infer that HUD use had no impact on approach success rate.

 Touchdown performance. As noted earlier, 13 of the 45 pilots conducted one or two go-arounds. The simulator failed to capture the location of the landing footprint for another 4 pilots. As a result, the data set for comparing the touchdown footprints across the HUD and no-HUD conditions consists of 28 pairs of approaches.

Of these 28 pairs of approaches, 9 were flown using the HUD in the first approach and 19 using the conventional head-down instruments (no-HUD) in the first approach; 14 were flown in standard RVR (700 m) conditions and 14 in lower than standard RVR conditions. The opportunistic nature of data collection precluded balancing the order of HUD use.

The main effect for HUD use, shown in Figure 9, is the only factor in the two-factor repeated-measures ANOVA to achieve statistical significance. As in Experiment 1, the effect for HUD use on the lateral component of the touchdown footprint is strong, F(1, 26) = 14.9, p < .001, n² = .10, indicating a power greater than .70. Once again, landings were closer to the centerline when pilots used the HUD. Because participant order was not fully counterbalanced, it is not possible to assess the potential for asymmetric transfer effects. As in Experiment 1, there was no significant effect for HUD use or RVR on the longitudinal component of the touchdown footprint. Once again, the difference in the observed variances across conditions of HUD use would be significant at  α = .10 if the data sets were independent.

There are three findings. First, HUD use per se did not influence the pilots’ decision to land or go-around at the decision height. The lack of an effect of HUD suggests that the additional information in the HUD did not distract the pilots’ attention or interfere with their decision making during the most critical portion of the approach and landing sequence. Second, HUD use significantly reduced the size of the lateral component of the touchdown footprint for all RVR conditions.

 Arguably it can be said that the difference between the HUD and the no-HUD conditions lay in the presence of a conformal flight-path vector in the pilots’ primary field of view during the landing. Third, in contrast to its effect on the lateral component of the touchdown footprint, it appears that the HUD did not influence the size of the longitudinal footprint. The first two findings conform to our hypotheses. Here we reexamine our hypotheses about the impact of HUD use on the touchdown footprint and offer an explanation for its differential impact on the lateral and longitudinal components.

 The HUD largely eliminates uncertainty about drift. The addition of a conformal flight-path vector projected over the runway provides instantaneous feedback about aircraft drift and actual flight path. The additional information enables precise control of the flight path during approach and landing and reduces the variance in lateral displacement practically to nil.

 Control of the longitudinal component of the touchdown footprint is largely an effect of how pilots handle the aircraft’s energy (operationally manifested as sink rate) in the final seconds before landing. The pilot uses information provided by the optic flow from the looming runway to control the aircraft’s energy (Lee, 1974). It is important to note that pilots of large commercial air transport aircraft are also aided by radio altimeter callouts that count down from 50 ft to 0 ft (runway contact) in 10-ft decrements. The initiation of the landing flare has been shown to be a function of time to contact (Mulder, Pleijsant, van der Vaart, & van Wieringen, 2000). A small change in the timing of a landing flare at the nominal glide slope of 3° results in large longitudinal differences. The HUD mode used in the experiments provided no flare guidance and no additional information that could be used to guide the pilots when to initiate the landing flare. So, if the pilots are relying more on timing of a flare maneuver than on velocity cues from the HUD to initiate the flare, it is easy to understand why we failed to detect any effect of the tested HUD with a flight-path symbol on longitudinal touchdown performance. It remains to be seen whether similar results are found for HUD modes with flare guidance, and which visual representations are actually most effective in prompting pilots to reduce sink rate at the optimal height above the runway.

 

CONCLUSIONS

Data from the experiments reported here show that HUD with a conformal velocity symbol (flight path) improved lateral touchdown performance, likely because the conformal flight-path vector in conjunction with the visual ground segment makes it easier for pilots to determine and correct for aircraft drift. We did not find an effect of HUD use on longitudinal touchdown performance, probably because the pilots flared the aircraft using a time-to-contact strategy, rather than using the flight-path vector available in the HUD modes studied here. The beneficial effects of HUD use on landing performance were seen in both in standard and lower than standard RVR conditions in both experiments, which implies that the minimum RVR for approaches using an HUD could be set lower than for approaches without an HUD.

BACKGROUND

 “Where is the nose of the aircraft?” 

It is shown as a flat vee with wings and is called a boresight.

 “Where is the horizon?”

It is below you, as shown by the synthetically drawn terrain.

The pilot’s primary focus is no longer where the aircraft is pointed, but where it is going. That is represented by the Flight Path Vector (FPV) and is drawn as a circle with small wings and a tail. The white horizontal line can be thought of as a horizon that has been adjusted to consider the altitude of the aircraft, as if the earth’s diameter has been increased. In some HUDs it is called a Zero Pitch Reference Line. You maintain level flight by placing the FPV on the Zero Pitch Reference Line.

The U.S. rules are given in 14 CFR 91.176 and are further explained in Advisory Circular 90-106A. If you meet the requirements of section (b) of that FAR, you can operate using EFVS to 100 feet above the touchdown zone elevation, at which point you must take over what the regulations call “natural vision” to complete the approach and landing. If you are operating under part 91K, 121, 129, or 135, you will need a management or operations specification. If you meet the requirements of section (a) of that FAR, you can operate using EFVS to touchdown and rollout. You will need a letter of authorization, management specification, or operations specification. AC 90-106A lists 1000 RVR as an adequate flight visibility and authorizations are normally written with this as a minimum.

Recent flight experience: EFVS. Except as provided in paragraphs (f) and (h) of this section, no person may manipulate the controls of an aircraft during an EFVS operation or act as pilot in command of an aircraft during an EFVS operation unless, within 6 calendar months preceding the month of the flight, that person performs and logs six instrument approaches as the sole manipulator of the controls using an EFVS under any weather conditions in the category of aircraft for which the person seeks the EFVS privilege. The instrument approaches may be performed in day or night conditions; and

(1) One approach must terminate in a full stop landing; and

(2) For persons authorized to exercise the privileges of § 91.176(a), the full stop landing must be conducted using the EFVS.

Source: 14 CFR 61, ¶61.66 (d)

comparison of flight director symbology

Click on image below to download it for visualization on large TV (magnification 9 times)

UNRESPONSIVE CIVIL AIRCRAFT TO AIR TRAFFIC CONTROL - NOT ALLOWED INTERCEPTING SUPERSONIC SPEED

 3.2.4 PROHIBITED AND RESTRICTED AREAS

3.2.4.1 Aircraft shall not be flown in aa PROHIBITED area, or in a RESTRICTED area the particular of which have been duly published, except in accordance with the conditions of the restrictions or by permission of the State over whose territory the areas are established.

Special Use Airspace (faa.gov)

The CIVIL jet plane did NOT offer any imminent threat to Washington's FRZ. It was flying leveled off on 34,000 feet during two overflight.

NORAD authorization for all F-16 fighter to make supersonic speed passage near the civil aircraft it was unprofessional and exhibitionist and, the supersonic passage produced severe WAKE TURBULENCE, which it resulted in intentional AUTOPILOT DESENGAGEMENT.

BRAZIL - MAY 10, 2023 - AZUL AIRLINES - FLIGHT AD 4372 - RUNWAY EXCURSION OVER LANDING at 04:35 GMT

 

Salvador airport, Bahia, Brazil (ICAO: SBSV) Runway length 2800 meters

SOURCES:

FLIGHTSAFETY FOUNDATION

Reducing the Risk of Runway Excursions

FAA 

AC No: 91-79A

Mitigating the Risks of a Runway Overrun Upon Landing

LANDING AND BRAKING TECHNIQUE. The flare, touchdown, and the braking technique, are also critical factors in completing a successful approach and landing maneuver. Landing and braking techniques are discussed below from a point at the beginning of the approach flare through a point at which the airplane decelerates to normal taxi speed or has been brought to a full stop.

The Flare. The flare reduces the approach rate of descent to a more acceptable rate for touchdown. If the flare is extended while additional speed is bled off, additional runway will be used. An extended flare may also result in an increase in pitch attitude which may lead to a tail strike. A firm landing does not mean a hard landing, but rather a deliberate or positive touchdown at the desired touchdown point. A landing executed solely for passenger comfort considerations, which extends the touchdown point beyond the TDZ, is not impressive, desirable, or consistent with safety or regulations. It is essential to fly the airplane onto the runway at the target touchdown point. Effects of an Extended Flare, as an example of the results of an extended flare.

(3) Be conservative and add 20 percent to the rollout distance if the pilot does not maintain maximum braking until the airplane reaches a full stop. Otherwise, if available, use AFM data for less than maximum braking.

(4) For airplanes that do not have antiskid brakes, spoilers, or thrust reverse, caution should be exercised. Excessive braking can lead to causing a tire failure or cause a skidding condition, leading to a runway excursion. Therefore, flying a stabilized approach and timely application of deceleration devices are the keys to a safe landing.

NOTE: Example: Available runway 5, 000 feet (ft), AFM landing distance 3,000 ft, at correct speed, and at 50-ft TCH, a total of 3 seconds to deploy the airplane’s deceleration devices, results in 1 second over the AFM landing distance assumed 2 seconds to deploy deceleration device will result in an additional 200 ft operational landing distance, for a total of 3,200 ft.

i. Landing with a Tailwind – Effect of a Tailwind on Landing Distance. The effect of a tailwind on landing distance is significant and is a factor in determining the landing distance required. Given the airplane will land at a particular airspeed, independent of the wind, the principal effect of a tailwind on operational landing distance is the change in the ground speed at which the airplane touches down.

(1) The effect of a tailwind will increase the landing distance by 21 percent for the first 10 kts of tailwind. (Refer to the Pilot’s Handbook of Aeronautical Knowledge, and the aircraft’sAFM/POH data to determine if tailwind landing data is available for the airplane.)

Aiming Point. The aiming point is the point on the ground at which, if the airplane maintains a constant glidepath and does not execute the round out (flare) maneuver for landing, it would touch the ground.

Mitigating the Risks of a Runway Overrun Upon Landing

This guidance pertains to the preflight planning requirements of Title 14 of the Code of Federal Regulations (14 CFR) part 91, §§ 91.103, 91.1037, and 91.605; part 121, § 121.195; and part 135, § 135.385.

The Effect of Excess Airspeed. The pilot must be aware of airspeed during the approach and of the targeted reference landing airspeed (VREF)/airspeed, plus wind gust adjustments, over the runway threshold. An excessive approach speed may result in an excessive speed over the runway’s threshold, which may result in landing beyond the intended touchdown point as well as a higher speed from which the pilot must bring the airplane to a stop. (Refer to the current editions of FSF ALAR Briefing Note 8.3—Landing Distances, and Boeing’s Takeoff/Landing on Wet and Contaminated Runways.)

Landing Beyond the Intended Touchdown Point. AFM/POH distances are based on a touchdown point determined through flight-testing procedures outlined in the current editions of AC 25-7 and AC 23-8. If the airplane does not touch down within the air distance included in the AFM or POH landing distance, it will not be possible to achieve the calculated landing distance.

f. Downhill Runway Slope. A negative runway slope of 1 percent (downhill) increases landing distance by 10 percent (a factor of 1.1). (Refer to FSF ALAR Briefing Note 8.3 and Appendix 1, Table 1-3, Sample Computation: Runway Length 7,000 ft.)

g. Excessive Height Over the Runway Threshold – Threshold Crossing Height (TCH) Greater Than 50 ft (Excess TCH). The certified landing distances furnished in the AFM are based on the landing gear being at a height of 50 ft over the runway threshold. For every 10 ft above the standard 50 ft threshold height, landing air distance will increase 200 ft.

NOTE: For example, TCH of 100 ft increases the landing distance by about 1,000 ft (50 additional ft divided by 10 = 5 X 200 ft landing distance increase per each 10 ft above 50 ft TCH = 1,000 ft additional landing distance). (Refer to FSF ALAR Briefing Note 8.3.).

THE EFFECTS OF COMPOUND FACTORS—THE END IS CLOSER THAN YOU THINK

Touchdown Point. Extended flare and runway slope are two factors that affect pilot control of the touchdown point. Turbine airplanes should be flown onto the runway rather than being held off the surface as speed dissipates. A firm landing is both normal and desirable. The typical operational touchdown point is in the first third of the runway, and it may be farther down the runway than the 1,000 ft point. This additional distance should be accounted for in the landing distance assessment at time of arrival (TOA).

NOTE: A 10 percent excess landing speed causes at least a 21 percent increase in landing distance. The excess speed places a greater working load on the brakes because of the additional kinetic energy to be dissipated. Also, the additional speed causes increased drag and lift in the normal ground attitude, and the increased lift reduces the normal force on the braking surfaces. The deceleration may suffer during this range of speed immediately after touchdown, and it is more probable for a tire to be blown out from braking at this point.

EFFECT OF WIND ON LANDING PERFORMANCE

Critical Condition Combinations. The most critical conditions of landing performance are combinations of:

• High gross weight, high density altitude,

• Wet/contaminated runway,

• Tailwind landing,

• Downhill slope,

• Less than maximum landing flap, and

• Short runway.

NOTE: In all cases, it is necessary to make an accurate prediction of minimum landing distance to compare with the available runway.

NEPAL - YETI AIRLINES 9N-ANC ATR 72-212A - NO ENGINES POWER

 

Source: Preliminary Report

On 15 January 2023, an ATR 72-212A was operating scheduled flights between Kathmandu (VNKT) and Pokhara International Airport (VNPR). The same flight crew operated two sectors between VNKT to VNPR and VNPR to VNKT earlier in the morning. The accident occurred during a visual approach for runway 12 at VNPR. This was the third flight by the crew members on that day. The flight was operated by two Captains, one Captain was in the process of obtaining aerodrome familarization for operating into Pokhara and the other Captain being the instructor pilot. The Captain being familarized, who was occupying the left hand seat, was the Pilot Flying (PF) and the instructor pilot, occupying the right hand seat, was the Pilot Monitoring (PM). 1.1.2 The take-off, climb, cruise and descent to Pokhara was normal. During the first contact with Pokhara tower the Air Traffic Controller (ATC) assigned the runway 30 to land. But during the later phases of flight crew requested and received clearance from ATC to land on Runway 12.

At 10:51:36, the aircraft descended (from 6,500 feet at five miles away from 

VNPR and joined the downwind track for Runway 12 to the north of the runway. 

The aircraft was visually identified by ATC during the approach. At 10:56:12, 

the pilots extended the flaps to the 15 degrees position and selected the landing 

gears lever to the down position. The take-off (TO) setting was selected on 

power management panel.

At 10:56:27, the PF disengaged the Autopilot System (AP) at an altitude of 721

feet Above Ground Level (AGL). The PF then called for “FLAPS 30” at 

10:56:32, and the PM replied, “Flaps 30 and descending”. The flight data 

recorder (FDR) data did not record any flap surface movement at that time. 

Instead, the propeller rotation speed (Np) of both engines decreased

simultaneously to less than 25%1 and the torque (Tq) started decreasing to 0%, 

which is consistent with both propellers going into the feathered condition2.

 

On the cockpit voice recorder (CVR) area microphone recording, a single Master 

Caution chime was recorded at 10:56:36. The flight crew then carried out the

“Before Landing Checklist” before starting the left turn onto the base leg. During 

that time, the power lever angle increased from 41% to 44%. At the point, Np

of both propellers were recorded as Non-Computed Data (NCD) in the FDR 

and the torque (Tq) of both engines were at 0%. When propellers are in feather, 

they are not producing thrust.

When both propellers were feathered, the investigation team observed that 

both engines of 9N-ANC were running flight idle condition during the event flight

to prevent over torque. As per the FDR data, all the recorded parameters 

related to engines did not show any anomaly. At 10:56:50 when the radio

altitude callout for five hundred feet3 was annunciated, another “click” sound 

was heard4. The aircraft reached a maximum bank angle of 30 degrees at this 

altitude. The recorded Np and Tq data remained invalid. The yaw damper 

disconnected four seconds later. The PF consulted the PM on whether to 

continue the left turn and the PM replied to continue the turn. Subsequently, 

the PF asked the PM on whether to continue descend and the PM responded 

it was not necessary and instructed to apply a little power. At 10:56:54, another 

click was heard, followed by the flaps surface movement to the 30 degrees

position.

When ATC gave the clearance for landing at 10:57:07, the PF mentioned twice 

that there was no power coming from the engines. At 10:57:11, the power 

levers were advanced first to 62 degrees then to the maximum power position.

It was followed by a “click” sound at 10:57:16. One second after the “click” 

sound, the aircraft was at the initiation of its last turn at 368 feet AGL, the high

pressure turbine speed (Nh) of both engines increased from 73% to 77%. 

It is noted that the PF handed over control of the aircraft to the PM at 10:57:18.

At 10:57:20, the PM (who was previously the PF) repeated again that there was 

no power from the engines. At 10:57:24 when the aircraft was at 311 feet AGL,

the stick shaker was activated warning the crew that the aircraft Angle of Attack 

(AoA) increased up to the stick shaker threshold.

At 10:57:26, a second sequence of stick shaker warning was activated when the aircraft banked towards the left abruptly. Thereafter, the radio altitude alert for two hundred feet was annunciated, and the cricket sound and stick shaker ceased. At 10:57:32, sound of impact was heard in the CVR. The FDR and CVR stopped recording at 10:57:33 and 10:57:35 respectively.

WAS IT A FLARE ACCIDENT OR LANDING ACCIDENT?

 

INVESTIGATION MUST REPORT IF THE ACCIDENT WAS A LANDING ACCIDENT OR A FLARE ACCIDENT

Mastering the Landing Flare/Round out

Pilot Perception

Analysis of 6,676 aircraft accident reports published by the National Transportation Safety Board

134 pilots with varying experience levels

Sources:

•           THE INTERNATIONAL JOURNAL OF AVIATION PSYCHOLOGY, 12(2), 137–152
•      Oklahoma State University
•      Department of Psychology
•      Laboratory of Comparative and  Behavioral Biology

           Danny Benbassat and Charles I. Abramson

•  Razia Rashid - founder of Psychology To Safety
•  ATSB RESEARCH AND ANALYSIS REPORT
• Aviation Safety Research Grant – B2005/0119

Aerial perspective is a monocular cue which is used for depth perception [the atmosphere causes distant objects to look hazy or blurry], which is used to judge how far away objects are. Monocular cues are named because they can occur only using one eye (as opposed to binocular cues which only occur with the use of both eyes).

Critical perceived time to contact (TTC)

Time remaining until the aircraft’s wheels make contact with the runway if no further action is taken (Mulder et al 2000).

TTC must be estimated directly, without first estimating speed and distance, based on the following ratio (known as tau):

TTC ≈ θ/(dθ/dt)

Where θ is the visual angle between the aimpoint and any other point on the ground plane at time one (see Figure above); and dθ/dt is the rate of change of this angle over time (Hoyle F 1957; Kaiser & Mowafy 1993; Lee, DN 1976).

Tau is a monocular cue to time-to-contact. During a landing, tau can be defined as the ratio of the angular distance between any two points on the ground (which happen to lie along the aiming line) divided by how fast this angular distance is increasing. Several other versions of tau have been proposed (see Regan & Gray 2000).

In more recent aviation research, Mulder and colleagues (2000) found mixed support for the proposals that flare timing is based on perceived runway angle (ψ) and perceived TTC (based on tau).

Study

The effects of pilot’s critical flare operation on long and hard landing events based on real flight Quick Access Recorder (QAR) data.

Flare accident rates

Causes for improper flares

The flare is the transition from a controlled descent to actual contact with the landing surface (Federal Aviation Administration [FAA], 1999; Grosz et al., 1995) and is also known as the flare out, round out, or level off (Jeppesen, 1985).

The task of determining the aircraft altitude above ground is crucial to a successful flare (Green, Muir, James, Gradwell, & Green, 1996) and is accomplished by the use of vision more than any other sense (FAA, 1999; Jeppesen, 1985; Menon, 1996; Nagel, 1988; Thom, 1992).

Depth Perception

Depth perception deals with the ability to see the environment in three dimensions and estimate distances of objects from us and from each other.

Aerial Perspective, objects at larger distances from us are affected by natural scattering of light and form less of a contrast with their background; making it harder to gauge a distance between the two and us.

Monocular cues operate when a person is looking with only one eye

 Pilots rely on monocular depth perception cues rather than binocular depth perception cues (Benson, 1999; Bond, Bryan, Rigney, & Warren, 1962; Langewiesche, 1972; Nagel, 1988).

Monocular depth perception is learned or dependent on experience (Benson, 1999; Bramson, 1982; Langewiesche, 1972; Love, 1995; Marieb, 1995; Tredici, 1996).

-          It is used by artists to induce depth in their two dimensional paintings. Thus, they are also called as the pictorial cues.

The monocular cues that help us in judging the depth and distance in two-dimensional surfaces:

·         Linear perspective: Imagine you are standing between the rail tracks and looking in the distance. You would see that the rail track become smaller and smaller, until there is a point where they meet each other. Linear perspective reflects this phenomena. It says that the distant between two objects far away appear to be smaller than what the distance actually is.

·         Interposition or overlapping:  This monocular cue occurs when one object covers the other. The object that is completely visible seems to be nearer and the object that is partially visible seems to be farther away.

·         Clearness: The more clear the object the nearer it seems. For example, on a hazy day a distant mountain would appear far away than on a clear day, because haze blurs the fine details. Therefore, if we see details of an object we perceive it closer.

·         Relative height: We perceive large objects to be closer to us and smaller objects to be farther away.

·         Motion parallax/ Movement: This cue occurs when the objects are in motion. The distant object appears to move slowly than the objects that are close.

Binocular cues operate when both our eyes are working together

Binocular depth perception is innate or acquired very early in life (Fox, Aslin, Shea, & Dumais, 1980; Kalat, 1998; Reading, 1983; Reinecke & Simons, 1974).

The cues that are provided by both the eyes working together:

·         Retinal or binocular disparity: Humans have two eyes which are horizontally separated by a distance of 6.5 centimeters. Because of this distance between two eyes the images formed on retina of a same object is slightly different. This difference in the images of two eyes is retinal disparity.

·         Convergence: when we see a closer object our eyes turn inward or converge, so that the image is formed on the fovea. Some muscles in our eyes send signal to the brain regarding the degree of convergence and our brain interprets it as a cue for depth perception. The more your eyes turn inward or converge the nearer the objects appear in the space.

·         Accommodation: The process by which ciliary muscles change the focal length of the eyes so that the image is clearly formed on the retina is called the accommodation of the eye. The accommodation varies for near and distant objects and also for objects moving away or towards the eye.

Failure to accurately determine aircraft altitude may result in flaring the aircraft too high (Gleim, 1998; King, 1999; Quinlan, 1999) or too low above the runway (Christy, 1991; Kershner, 1981; Love, 1995).

Improper flares also increase brake, nosewheel tire, and nosewheel shimmy dampener wear (on Cessnas; Christy, 1991; Jorgensen & Schley, 1990).

Improper flares may affect pilot self-esteem and selfefficacy.

The flare maneuver was defined as the ability to determine 10 to 20 ft from the ground and initiate the leveloff.

Three groups of pilots (novice, intermediate, and expert) were surveyed with purposive sampling.

Participants were 134 pilots (novice = 55, intermediate = 45, expert = 34) from three Part 141-approved flight schools in the state of Oklahoma.

Pilot perceptions were assessed with a 21-item questionnaire.

Pilots were asked to rate the flare maneuver and nine other randomly selected standard flight maneuvers for the level of difficulty on a scale ranging from 1 (extremely easy) to 7 (extremely difficult) under optimal conditions (i.e., no wind, 10 miles visibility).

After rating the 10 items, pilots turned the page and learned that the study was specific to the landing flare.

In Item 11

Pilots were provided with the number of total annual U.S. landing accidents and were asked to estimate the number of annual flare accident frequencies.

In Item 12

Pilots were asked to indicate how confident they were in their estimates of annual flare accident frequencies on a scale ranging from 1 (low confident) to 7 (high confidence).

The next items were not only specific to the landing flare but also to their ability to determine when to initiate the flare, that is, estimate 10 to 20 ft from the ground.

In Item 13

Pilots imagined that they were transitioning from descent attitude to flare attitude and indicated how confident they were that their aircraft was 10 to 20 ft from the ground on a scale ranging from 1 (low confidence) to 7 (high confidence).

In Item 14

Pilots recalled their first solo flare attempts and rated factors that assisted them in determining the aircraft altitude before initiating the flare (CFI instruction, instrument readings, practice, pilot manual, ground-school training, other) on a 7-point-scale ranging from 1 (not at all) to 7 (to great extent).

In Item 15

After a reminder that pilots flare the aircraft 10 to 20 ft from the ground, ascertained how pilots rated the task of judging altitude when initiating the flare on a scale ranging from 1 (very easy) to 7 (very difficult).

In Item 16

Pilots imagined that they were on approach for landing and were asked to choose how they determine when to initiate the flare. how did they know they were 10 to 20 ft from the ground (instrument readings, gut reaction, I don’t, sense of sight, sense of balance, other).

In Item 17

Pilots were asked to indicate if there was a need for improved flare-training methods, on a scale ranging from 1 (definitely yes) to 7 (definitely no).

In Item 18

To what factors (pattern practice, natural ability, sheer luck, aviation books, my instructor, other) did they attribute their current successful landing flares, on a scale ranging from 1 (not at all) to 7 (to great extent).

Items 19 and 20 (reiterated Items 16 and 18)

Required pilots to elaborate and explain their responses. Pilots were instructed to think carefully before they answered and be as specific as possible.

In Item 21

Pilots were asked to indicate what type of visual information assisted them in determining when to initiate the flare.

CONCLUSION

 Overall, 6,676 accident reports produced by the NTSB were analyzed for flare accident rates.

Flare accidents

Proper flares depend on monocular cues, and monocular cues depend on experience (Hawkins, 1993; Rinalducci, Patterson, Forren, & Andes, 1985).

On average, the flare only lasts approximately 6 sec and a pilot with a total time of 5,000 hr only has approximately 8 hr of flare time (King, 1998).

In more recent aviation research, Mulder and colleagues (2000) found mixed support for the proposals that flare timing is based on perceived runway angle (ψ) and perceived TTC (based on tau).

Critical perceived runway angle (ψ)

Pilots could initiate the landing flare when the visual angle (ψ) formed between the left and right edges of the runway at the aiming line reaches a critical value (Mulder et al, 2000).

In fact, pilots use different cues or combinations of monocular cues. For example, overall, the horizon and end of runway, shape of runway or runway markings, and familiar objects were the most frequent visual cues that pilots used to estimate their altitude during the flare.

However, University of Oklahoma pilots most frequently used the horizon or end of runway, whereas Oklahoma State University pilots used the shape of runway or runway markings.

Softer throttle reduction is helpful for a better flare performance. Not immediately IDLE. 

The force of the engines and of gravity are driving the airplane down and forward. When you rotate the nose up for the flare, some of the energy that was used to propel the airplane forward is now used to further arrest the force of gravity. You have less force available for forward motion, your speed necessarily decreases.

Flare energy

The rotation-to-flare requires energy to arrest downward momentum; the amount of energy required depends on the glide path angle, any differences in aircraft speed from target speed, and any acceleration/deceleration. It will be to your advantage to make the angle and speed differences the same for every landing.

The rotation-to-flare may or may not bleed airspeed, depending on aircraft flight idle and ground effect characteristics. Here are three examples:

 B747 — The combination of a very large wing span induced ground effect perfectly compensates for energy needed to arrest the descent. Once the descent has been arrested, the flight idle and ground effect result in no airspeed loss at all under most conditions. The airplane has to be flown onto the runway, it will not run out of speed and sit itself down.

GV — The GV also has a very large wing span and high flight idle engines. The descent can be arrested with very little loss of speed, but the airplane does lose speed gradually if held inches off the runway. But, once again, it should be flown onto the runway to avoid a long landing.

G450 — The G450 will lose about 5 knots in the rotation to flare, which is precisely the minimum speed increment to VREF. Once the rotation to flare is made, speed decay continues as flight idle and ground effect are not enough to maintain speed. Any exaggerated flare for the sake of touchdown will result in a significant loss of speed. Once again, the airplane should be flown onto the runway.

VERY SOFT LANDING

The FLARE curve it has two breaking points: The first, it is on (Xf, Hf) [Glide Slope breaking point] and the second one it is on Xtd flare breaking point [Flare breaking point it is at the touchdown point]. Ideally, from this point on the flare curve must be tangent to runway surface to make a soft landing.

Very soft landing, it is that the Pilot Flying does not let the green curve flare segment [beyond Xtd point] to descend below X axis.

That green curve segment after the touchdown point it can NOT descend below the X axis. 

It does tangent on the runway surface plane for smoothing landing.

When to flare

What "the book" says:

"Very few manufacturers specify a flare height. Gulfstream, for example, leaves you off at 50 feet and the next thing you know, you are in the touchdown zone. Some Bombardier manuals say, "at or below 50 feet." About the only manufacturer that does print a height is Boeing. In their Boeing 777 Flight Crew Training Manual, they say this: "Initiate the flare when the main gear is approximately 20 to 30 feet above the runway by increasing pitch attitude approximately 2° - 3°. This slows the rate of descent." That pretty much agrees with what we did in the Boeing 747." 

You should consult your manufacturer's books.

HINT

Pilot after crossing over threshold at the height 50 ft for landing MUST NOT LET his/her eye corners to capture any lateral vision, mainly Pilot Flying, because of lateral vision illusion which induces pilot to see a relative movement speeding up the plane. That false relative speed up produces a sensation of runway length it would be shortening very quickly. Runway excursion.