GLIDE FLIGHT – HOW TO - Azerbaijan Airlines EMB-190AR Flight J28243 and Air Transat Flight 236 A330-243

 

Captain struggling to not let the plane plunge into the sea

How far can a commercial aircraft fly with total engine failure?

Sources:

Airplane Flying Handbook FAA-H-8083-3C

Les Glatt, Ph.D, ATP/CFI-AI, AGI/IGI

Brown & Brown Insurance Brokers (UK) Limited

Accident Investigation Final Report

All Engines-out Landing Due to Fuel Exhaustion

Air Transat

Airbus A330-243 marks C-GITS

Lajes, Azores, Portugal

24 August 2001

FlightRadar24

Azerbaijan Airlines Airbus 330-243 almost plunged into the Caspian Sea before the accident in Kazakhstan

The gray color graphic line [Vertical rate (feet per minute)] shows the plane climbing up and down and the captain struggling to not let it plunge into the sea, as illustrated on the image below.

Captain struggling to hold the flight level

How far can a commercial aircraft fly with total engine failure?

The furthest flown by a passenger jet without engines was in 2001. An Air Transat Flight 236 was a transatlantic flight bound for Lisbon, Portugal, from Toronto, Canada. The plane carrying 293 passengers and 13 crews lost all engine power because of fuel leak, so it ran out of fuel caused by improper maintenance while flying over the Atlantic Ocean on August 24, 2001, as unbeknownst to anyone it had been leaking fuel ever since leaving Toronto six hours prior. Without any power, Captain Robert Piche and First officer Dirk DeJager glided the Airbus A330 for 19 minutes, covering 75 miles before landing safely at Lajes Air Base.

 It is necessary that they be performed more subconsciously than other maneuvers because most of the time during their execution, the pilot will be giving full attention to details other than the mechanics of performing the maneuver.

A glide is a basic maneuver in which the airplane loses altitude in a controlled descent with little or no engine power.

Forward motion is maintained by gravity pulling the airplane along an inclined path, and the descent rate is controlled by the pilot balancing the forces of gravity and lift.

FLIGHT INSTRUCTORS MUST FORGE ON STUDENT-PILOT’S MIND THAT TWO IDENTICAL AIRCRAFT AFTER INCURING IN TOTAL ENGINES FAILURE, BOTH PLANES WITH DIFFERENT WEIGHTS, THEY WILL REACH THE SAME DISTANCE FLYING ON GLIDE PATH ANGLE

Pitch angle = FPA + AOA

Pitch Angle = Flight Path Angle + Angle-of-Attack

(below the horizontal) + (chordline is above the velocity vector)

Glides are directly related to the practice of power-off accuracy landings.

They have a specific operational purpose in normal landing approaches and forced landings after engine failure.

The glide ratio of an airplane is the distance the airplane travels in relation to the altitude it loses. For example, if an airplane travels 10,000 feet forward while descending 1,000 feet, its glide ratio is 10 to 1.

The best glide airspeed is used to maximize the distance flown.

This airspeed is important when a pilot is attempting to fly during an engine failure.

When gliding at airspeed above or below the best glide airspeed, drag increases.

The best airspeed for gliding is one at which the airplane travels the greatest forward distance for a given loss of altitude in still air.

Source: Les Glatt, Ph.D, ATP/CFI-AI, AGI/IGI

(1) When the engine fails, the first step is to establish the aircraft at the airspeed

for best glide.

(2) This best glide airspeed allows the aircraft to fly at its maximum L/D ratio,

which allows the aircraft to glide the farthest horizontal distance for the least

loss in altitude.

(3) The best glide airspeed is given in the POH in the section entitled

“Emergency Procedures”.

(4) The airspeed that is shown is for the aircraft being loaded to gross weight.

(5) A rule of thumb to obtain the best glide speed at any aircraft weight is to

reduce the best glide airspeed at gross weight by one-half the percent

reduction in gross weight. Thus, if the aircraft is loaded to 10% below gross

weight, you should reduce the best glide speed at gross weight by 5%.

This relationship is the most fundamental relationship for gliding flight.

It gives us the flight path angle as a function of the lift to drag ratio.

The L/D can also be obtained from the POH by viewing the “Maximum Glide” chart in the “Emergency Procedures” section. Figure 3 shows a “Maximum Glide” chart” for a C-172. Note that this chart corresponds to a C-172 at gross weight, 65KIAS, propeller windmilling, flaps up and zero wind.

The L/D ratio can be obtained by dividing the 18 nautical mile distance in feet by the height above the terrain at 18 nautical miles, which is 12000 feet. This ratio is determined to be 9.09. If one substitutes the value of L/D of 9.09 into the glide path equation (5), the flight path angle is determined to be 6.3 degrees below the horizon.

This glide path angle is independent of the aircraft altitude or weight of the aircraft.

In the case of a C-172, the flight path angle was shown to be 6.3 degrees below the horizontal. The maximum L/D for a C-172 occurs somewhere between 6- and 9-degrees angle-of-attack. Using the expression in equation (1), the pitch angle would be somewhere between 0 and 3 degrees above the horizon. Thus, basic aerodynamics tells us that the same pitch attitude should be flown, independent of the weight of the aircraft or the altitude. The exact pitch attitude can be determined either by a plot similar to Figure 4 for a C-172, or one can load the aircraft to gross weight, reduce the power to idle and trim the aircraft to 65KIAS. The pitch attitude for the best glide speed should be noted and that pitch attitude should be used for simulated emergencies, no matter what the weight of the aircraft.

Flight instructors should teach student pilots to establish a given pitch attitude

when simulating engine failures, rather than to chase the airspeed, which is going to be dependent on the weight of the aircraft. By establishing the proper pitch attitude at different aircraft weights, the student can observe the resultant airspeeds for the same pitch attitude and thus correlate that with the statement that “the best glide

 speed is reduced by half the percent reduction in gross weight”. We try to teach our students to maintain visual cues outside the aircraft and setting up a specific pitch attitude for engine-out emergency simulations allows the student to do just that, keep his head out of the cockpit.

A stabilized, power-off descent at the best glide speed is often referred to as a normal glide. The beginning pilot should memorize the airplane’s attitude and speed with reference to the natural horizon and note the sounds made by the air passing over the airplane’s structure, forces on the flight controls, and the feel of the airplane.

 Example

Consider an executive jet that has a weight of 10,000 lbs, a wing area of 200 ft², and a parabolic drag polar*

We would like to calculate the glide range and L endurance from 20,000 ft. We would like to compare the range and endurance for a max range flight condition with that for a max endurance flight condition.

* Parabolic Drag Polar, it shows the aerodynamic efficiency of a given aircraft - that is, it represents the lift-to-drag ratio.

 An Exact Solution for Glide Endurance

 It turns out that we can get an exact solution for the glide time if we assume a standard atmosphere. The equation we developed for sink rate is:

05:45	The crew initiated a diversion from the flight-planned route for a landing at the Lajes (LPLA).
05:48	The crew advised Santa Maria Oceanic Control that the flight was diverting due to a fuel shortage.
06:13	The crew notified air traffic control that the right engine (Rolls-Royce RB211 Trent 772B) had flamed out.
06:26	When the aircraft was about 65 nautical miles from the Lajes airport and at an altitude of about FL 345 [34,500 feet], the crew reported that the left engine had also flamed out and that a ditching at sea was possible.
06:45	The aircraft landed on runway 33 at the Lajes airport.