WET RUNWAY LANDING DISTANCE CORRECTION - TRANSDUCER IN MAIN WHEELS - NO REVERSERS - HIGH SPEED

 

UBATUBA (SDUB) SP, BRAZIL 23° 26' 29" S, 045° 04' 34" W

RWY 09 FST 380M CLSD for LDG

TRANSDUCER SIGNALS WHEEL LOWER RPM COMPARED TO THE OTHER WHEEL

14 CFR 135.385(b), and says (in part):

no person operating a turbine engine powered large transport category airplane may take off that airplane unless its weight on arrival ... would allow a full stop landing at the intended destination airport within 60 percent of the effective length of each runway

So to follow the regulation by the letter, you need to take 60% of the runway length and compare it to your actual landing distance.

 Nenhuma pessoa operando um avião de grande categoria de transporte movido a motor com turbina pode decolar esse avião, a menos que seu peso na chegada ... permitiria um pouso completo no aeroporto de destino pretendido dentro de 60% do comprimento efetivo de cada pista.

Portanto, para seguir o regulamento juridicamente, você precisa pegar 60% do comprimento da pista e compará-lo com a distância real de pouso.

 14 CFR 135.385(d) says:

(d) Unless, based on a showing of actual operating landing techniques on wet runways, a shorter landing distance (but never less than that required by paragraph (b) of this section) has been approved for a specific type and model airplane and included in the Airplane Flight Manual, no person may take off a turbojet airplane when the appropriate weather reports or forecasts, or any combination of them, indicate that the runways at the destination airport may be wet or slippery at the estimated time of arrival unless the effective runway length at the destination airport is at least 115 percent of the runway length required under paragraph (b) of this section.

 (d) A menos que, com base na demonstração de técnicas reais de pouso operacional em pistas molhadas, uma distância de pouso mais curta (mas nunca inferior à exigida pelo parágrafo (b) desta seção) tenha sido aprovada para um tipo e modelo de avião específico e incluída no Manual de Voo do Avião, nenhuma pessoa pode decolar um avião turbojato quando os boletins meteorológicos ou previsões meteorológicas apropriados,  ou qualquer combinação deles, indicam que as pistas do aeroporto de destino podem estar molhadas ou escorregadias no horário estimado de chegada, a menos que o comprimento efetivo da pista no aeroporto de destino seja de pelo menos 115 por cento do comprimento da pista exigido no parágrafo (b) desta seção.

So basically, you use the information from your AFM for wet runway landing distance, or if it isn't provided (since it isn't required), you do the same calculation that you did before but include an additional 15%.

Então, basicamente, você usa as informações do seu AFM para a distância de pouso na pista molhada ou, se não for fornecida (já que não é necessária), você faz o mesmo cálculo que fez antes, mas inclui um adicional de 15%.

Cada vez que um pneu principal passa em uma poça de água, a RPM (Rotação Por Minuto) desta roda diminui muito em relação à outra roda no outro lado que não está passando em poça de água (RPM maior).

A roda que passa na poça de água, contém um dispositivo chamado TRANSDUCER, o qual compara as RPM das duas rodas e libera a rotação da roda mais LENTA. Neste instante esta roda mais lenta não aceita FREIO, pois está precisando girar mais rápido para acompanhar a rotação da roda do outro lado (mais rápida), em sendo assim, o avião não consegue diminuir significativamente a velocidade. Diminui, mas não o suficiente para parar.

Each time a main tire passes through a puddle of water, the RPM (Rotation Per Minute) of this wheel decreases greatly relative to the other wheel on the other side that is not passing through a puddle of water (higher RPM).

The wheel that passes through the puddle of water contains a device called TRANSDUCER, which compares the RPM of the two wheels and releases the slower wheel rotation. At this moment, this slower wheel does not accept BRAKES, because it needs to rotate faster to keep up with the rotation of the wheel on the other side (faster), so the plane cannot significantly slow down. It decreases, but not enough to stop.

PT - DYB LEARJET 45 - TAILWIND LANDING AND MIRRORED WET RUNWAY AND SHORT REMANESCENTE STOP DISTANCE

 

PP - DYB Learjet 45

Better viewing on full screen

All people on board are alive

The plane took off from CHAPECO, SC, BRAZIL [SBCH 27° 08' 02" S, 052° 39' 32" W]  around 17:00 UTC [14:00 BRT] to a short flight for 13 minutes [70 Km = 37,8 NM] to land in ERECHIM, RS, BRAZIL [SSER 27° 39' 48" S, 052° 16' 19" W].

The Learjet 45 had its landing with tailwind above the tailwind limit recommendation of 10 Knots.

We can watch on video the windsock showing wind speed above 10 Knots and swinging in variable directions.

Runway length has 1280 meters.

AERODROME OBSTICLES

- OBS OBST (Antenna) DIST 2564 meters from THR 14, AZM 328 DEG, HGT 280 ft;

- OBS OBST (Antenna) DIST 3434 meters from THR 14, AZM 002 DEG, HGT 475 ft;

- OBS OBST (Antenna) DIST 3701 meters from THR 14, AZM 007 DEG, HGT 408 ft;

- OBS OBST (Antenna) DIST 3059 meters from THR 14, AZM 016 DEG, HGT 347 ft;

- OBS OBST (Antenna) DIST 1604 meters from THR 14, AZM 037 DEG, HGT 182 ft;

Compulsory TFC Circuit by AD SECT SW

In line with Federal Aviation Administration (FAA) specifications, windsocks may be orange, yellow, or white and may not have any logos or lettering. The most useful windsocks for determining wind speed are those with stripes of alternating colors, such as orange and white, or lines at set intervals.

The red and white striped windsock is the most common version, but windsocks of many different colors are used for specific applications where a colorful windsock may not be suitable. Nature reserves tend to only allow green windsocks to prevent color pollution, for example.

The FAA has specific windsock specifications to ensure that you do not end up incorrectly reading a makeshift windsock at a remote aerodrome.

The FAA specifies that the windsock length must be either eight feet [243 cm] with a throat diameter of 18 inches [46 cm] or a length of 12 feet [366 cm] with a throat diameter of 36 inches [15 cm] . The fabric used must be water-repellant and colorfast, as the windsock will be constantly exposed to the elements.

The entire windsock assembly must be able to operate in a temperature range of -67 degrees Fahrenheit (-55 degrees Celsius) to 131 degrees Fahrenheit (55 degrees Celsius) and must be able to sustain wind speeds of up to 75 knots. [139 Km/h]

How to Estimate Wind Speeds

Using the stripes of a windsock, a reasonably accurate estimate of the wind speed can be made.

Each stripe of a windsock represents 3 knots of wind. In other words, the windsock will orientate itself with the wind direction and extend the first stripe when the wind speed reaches 3 knots. When the second stripe extends, the wind speed is 6 knots, and so on, until all stripes are extended when the wind speed is 15 knots or more.

I have been suggesting to pilots to keep on their minds interpreting windsock speed based on windsock angles [ 0 (zero), 45° and 90° ) as illustrated at the right.

Emirates B777-300 Flight EK521 Tailwind Shared in Accident

PRELIMINARY REPORT

As the flight neared Dubai, the crew received the automatic terminal information service (ATIS) Information Zulu, which included a windshear warning for all runways.

The Aircraft was configured for landing with the flaps set to 30, and approach speed selected of 152 knots (VREF + 5) indicated airspeed (IAS) The Aircraft was vectored for an area navigation (RNAV/GNSS) approach to runway 12L. Air traffic control cleared the flight to land, with the wind reported to be from 340 degrees at 11 knots, and to vacate the runway via taxiway Mike 9.
During the approach, at 0836:00, with the autothrottle system in SPEED mode, as the Aircraft descended through a radio altitude (RA) of 1,100 feet, at 152 knots IAS, the wind direction started to change from a headwind component of 8 knots to a tailwind component. The autopilot was disengaged at approximately 920 feet RA and the approach continued with the autothrottle connected. As the Aircraft descended through 700 feet RA at 0836:22, and at 154 knots IAS, it was subjected to a tailwind component which gradually increased to a maximum of 16 knots.
At 0837:07, 159 knots IAS, 35 feet RA, the PF started to flare the Aircraft. The autothrottle mode transitioned to IDLE and both thrust levers were moving towards the idle position. At 0837:12, 160 knots IAS, and 5 feet RA, five seconds before touchdown, the wind direction again started to change to a headwind.
As recorded by the Aircraft flight data recorder, the weight-on-wheels sensors indicated that the right main landing gear touched down at 0837:17, approximately 1,100 meters from the runway 12L threshold at 162 knots IAS, followed three seconds later by the left main landing gear. The nose landing gear remained in the air.
At 0837:19, the Aircraft runway awareness advisory system (RAAS) aural message “LONG LANDING, LONG LANDING” was annunciated.

At 0837:23, the Aircraft became airborne in an attempt to go-around and was subjected to a headwind component until impact. At 0837:27, the flap lever was moved to the 20 position. Two seconds later the landing gear lever was selected to the UP position. Subsequently, the landing gear unlocked and began to retract.
At 0837:28, the air traffic control tower issued a clearance to continue straight ahead and climb to 4,000 feet. The clearance was read back correctly.
The Aircraft reached a maximum height of approximately 85 feet RA at 134 knots IAS, with the landing gear in transit to the retracted position. The Aircraft then began to sink back onto the runway. Both crewmembers recalled seeing the IAS decreasing and the Copilot called out “Check speed.” At 0837:35, three seconds before impact with the runway, both thrust levers were moved from the idle position to full forward. The autothrottle transition from IDLE to THRUST mode. Approximately one second later, a ground proximity warning system (GPWS) aural warning of “DON’T SINK, DON’T SINK” was annunciated.
One second before impact, both engines started to respond to the thrust lever movement showing an increase in related parameters.
At 0837:38, the Aircraft aft fuselage impacted the runway abeam the November 7 intersection at 125 knots, with a nose-up pitch angle of 9.5 degrees, and at a rate of descent of 900 feet per minute. This was followed by the impact of the engines on the runway. The three landing gears were still in transit to the retracted position. As the Aircraft slid along the runway, the No.2 engine-pylon assembly separated from the right hand (RH) wing. From a runway camera recording, an intense fuel fed fire was observed to start in the area of the damaged No.2 engine-pylon wing attachment area. The Aircraft continued to slide along the runway on the lower fuselage, the outboard RH wing, and the No.1 engine. An incipient fire started on the underside of the No.1 engine.
The Aircraft came to rest adjacent to the Mike 13 taxiway at a magnetic heading of approximately 240 degrees. After the Aircraft came to rest, fire was emanating from the No. 2 engine, the damaged RH engine-pylon wing attachment area and from under the Aircraft fuselage. Approximately one minute after, the Commander transmitted a “MAYDAY” call and informed air traffic control that the Aircraft was being evacuated.