Rookie Error: Forgetting to Bring Up the Landing Gear During Flight
This is a guest post by my friend Matthew Warburton, looking at the recent incident of Air India Flight AI676. I hope you enjoy it!
Rookie errors can happen to any of us, no matter who we are or what we are doing. The difference is that any mistake can be very costly when you are flying a commercial airliner! It’s difficult to imagine that trained and professional pilots could forget to bring up the landing gear during a flight, but that’s exactly what happened as recently as July 2017, when two pilots were suspended following an incident on Air India Flight AI676.
The Airbus A320 left Kolkata, carrying 99 passengers on a journey that was supposed to last two and a half hours, with the final destination set for Mumbai. But the plane didn’t land in Mumbai. It nearly ran out of fuel mid-flight and had to be redirected to avoid serious consequences. The pilots had failed to retract the landing gear!
It was around 90 minutes into the flight that the pilots requested permission to redirect the aircraft and land in Nagpur. The pilots had, thankfully, noticed that the fuel gauge was dropping rapidly, and knew that they would not make it all the way to their expected destination.
In fact, sources have revealed that the plane even struggled to reach its regular altitude after taking off. It should have ascended to around 35-37,000 feet, where the air is thin enough to allow the plane to run efficiently on the fuel that it has. In reality, the plane was flying at only around 24,000 feet, low enough that the dense air would require more petrol to fly through. The plane was also noted to be flying at only 230 knots, compared to its usual pace of 500 knots.
The extra drag of the wheels, the negative effects on aerodynamics, and the lower flight altitude had caused an increased fuel consumption rate, which could have been fatal. Just like you might have experienced in popular video games like PokerStars Power Up, energy conservation is a critical component of a successful flight. Had the pilots not noticed the fuel and decided to divert to the closer airport at Nagpur, the outcome could have been very different. It was on final approach to Nagpur when the flight crew went to lower the gear that they realized that it was already extended.
But what is really unusual is that none of the passengers on board the flight reported anything to their pilots. The situation would have caused intense vibrations, loud noises and overall a very low quality of flight. One theory is that the dearth of complaints might be due to the fact that the plane was travelling during monsoon season, and the passengers attributed these effects to weather conditions.
What is even more fascinating is that the pilots themselves, who were suspended following the incident, did not notice that the landing gear was down until they actually came to land in Nagpur! They had struggled to gain altitude or speed, had burned off fuel at an alarming rate, and had ignored a basic procedure on the post-take off checklist; they had not checked that the landing gear had been retracted.
The pilots of Air India Flight AI676 teach us a very valuable lesson. They show us that even trained and professional pilots can make elementary mistakes. They teach us that we must always remember the basics!
I agree with Matthew: this case shows how easy it can be to miss the obvious. With such a lack of situational awareness, it’s a relief that they noticed the low fuel!
The incompetence of this crew is such that one would wonder if they had managed to get into the cockpit with a booklet called “Bluffers’ Guide’ !
Wasn’t there a movie some time ago called “Catch me if you can?”. The main character pretends to be the captain of an airline and gets into the cockpit. The scene that follows will only amuse someone who has absolutely no idea how procedures work in an airline. More like a slapstick film where either guy thinks that the other is the instructor and they only find out when they are in the air.
Mix those two scenes and you have the scenario of the flight described here: two guys in an aircraft, full of passengers, in the air. And neither has a clue !
Scary!
PS.
Of course the B737 would not use “petrol” but Jet A1 or JP4. But that is a forgivable slip of the pen or keyboard. Forgetting to raise the wheels on an airline flight is not !
Oh hell. I proofed the piece and didn’t spot that!
and my slip is Boeing iso A320
I saw this in the news and I thought “hm. wonder what was wrong with the gear?” – I figured it was the typical clueless journalism I’ve come to associate with technical matters.
Nope. Crew forgot to retract it. They couldn’t figure out why they couldn’t reach cruising altitude/speed. Seriously.
Yup, that’s my jaw rattling around on the ground now.
Yes, alarming. I also recall an Air India A320 landing accident many years ago not long after the type was introduced, again due to poor crew training and airmanship. By the way the cruising speed of the A320 at cruising altitude is nearer 340 knots (Mach 0.80)not 500 knots.
Wikipedia, citing Airbus literature, says “Cruise: Mach 0.78 (447 kn; 829 km/h)”
I believe converting Mach to knots requires knowledge of the altitude. The 0.78 = 447kn seems to be calculated at 35,000 ft which is a reasonable cruising altitude. I can’t see how @Cam gets 340 kn from Mach 0.8 though.
Cliff, you are absolutely correct. I took my info from Airliners.net which was obviously wrong. I should have referred to the Airbus website. Lesson learnt- use caution when relying on Google for a quick answer!
The airspeed is not really relevant in this case – they never got up to the normal cruising speed anyway.
Once climbing into the higher flight levels the aircraft speed will indeed be expressed in Mach number but that is not the same at different altitudes and depends also on factors like air temperature.
For whoever is interested:
Strictly speaking, the Airbus would not have had an abnormally high fuel flow, the engines would not have know the difference between gear “up” or gear “down”, nor would the flap- or slat position have made a difference (they were retracted, I suppose0.
What DID cause the low fuel emergency was:
1. The aircraft never reached its cruising level. Jet engines guzzle fuel at lower levels. Fuel flow starts tapering off at levels above FL300 and really drops in earnest above FL 350. The weight of the aircraft will decide if it is better to stay a bit lower, fly faster and accept a (slightly) higher fuel flow or climb (or struggle) to a higher altitude where the lower fuel flow will offset the loss of speed. Especially with a jet stream on the route, this factor can be determining.
The extended undercarriage did not affect actual fuel flow (at the actual level), but combined with the (considerably) higher fuel burn per hour the low speed would have caused a longer period in the air, resulting in a larger amount of fuel being burned:
– It burned more per hour due to the lower level,
– It flew at a lower speed, covering less distance for each unit of time.
– It spent more time whilst burning more fuel.
The old Lear had an MMO of M.81 and could easily cruise at that speed at very high levels (FL 470. on occasion 490, even 510). Problem was that a sudden change in temperature could cause the aircraft to exceed the MMO, triggering a “Mach puller”. Many private owners wanted to keep up the speed, which corresponded if I remember well to about 470 kts TAS. In order to prevent the puller coming in, some pulled the circuit breaker. It caused a few crashes. But in the case of this A320, the crew never noticed that they were very slow, were using too much fuel and could not reach their planned level. What I find strange is that ATC never seemed to have noticed anything unusual, either. If an aircraft is cleared to a certain level and never reaches it, most ATC controllers at a minimum will start asking questions.
This entry raises many questions, not least about the level of crew training in Air India. Neither crew member would have passed a proficiency check in a major airline, or any airline with a decent crew training syllabus that I am aware of. Air India IS a major airline and I would expect with the resources to keep a training department, regular simulator sessions, recurrent training and the like. Even if crews are hired fully rated as direct entry, an airline still will require them to be put through a training course where they would be assessed and taught to operate in accordance with the company SOP’s.
So it is still a mystery how these pilots, judging from this article definitely below acceptable standard, managed to slip through the net.
And it is a bit worrisome, too.
Is the A320 so easy to fly that even a pilot who is not “up to scratch” can pass his or her checks undetected?
Or had they been attending a party the previous night?
It’s always been my understanding that the speed of sound is affected by temperature, not altitude.
It is a function of density, which is affected by both pressure and temperature.
Ernest Walk is correct: the speed of sound is primarily affected by temperature (for an ideal gas, it’s *only* affected by temperature and molecular composition).
The speed of sound in an ideal gas can be expressed as being proportional to the square root of pressure over density, but since pressure is proportional to the product of density and temperature, the density then cancels out, leaving you with just the square root of temperature.
https://en.wikipedia.org/wiki/Speed_of_sound
In the lower atmosphere (up into the beginnings of the stratosphere), temperature and density both fall with increasing altitude, as does sound speed. As you go higher in the stratosphere, the temperature increases, and so does the speed of sound, even though the density continues to fall.
https://en.wikipedia.org/wiki/Speed_of_sound#/media/File:Comparison_US_standard_atmosphere_1962.svg
To give a more extreme example: in the rarified and extremely hot gas found between galaxies in a galaxy cluster, the density is about 10^22 (a 1 followed by 22 zeros) times lower than in the Earth’s atmosphere, while the temperature is about 100,000 times higher. The sound speed in the cluster gas turns out to be several hundred kilometers per second, compared with about 0.3 kilometers per second for the lower atmosphere of the Earth. So: temperature, not density.
Reminds me of another case where a pilot trashed his entire aircraft by retracting the landing gear while parked at the gate.
Unfortunately his incompetence caught up to him and years later when he made a controlled flight into terrain.
As a Captain I have ferried a B727 with the gear extended . I can tell you that the noise is extremely loud and talking in the cockpit is almost impossible. I can’t understand why this crew didn’t experience that.
The problem with this incident is that all we have to go on are newspaper reports. I tried to find an incident report on the AAIB website, but I can’t read the language and didn’t find where they keep their more recent reports — and if they don’t issue them in English, I’d have another probem! (Might be worth giving it a go with Google Translate?)
Now if we assume that the issue is very noticeable, we should assume that it has been noticed (one punter suspected noise-cancelling headsets, but…). One reason to not retract the gear in flight might be that it can’t be retracted because the ground pins were accidentally not removed. In this situation, if you’re overweight, you can then either burn off fuel and land where you started from (if metereologically possible), or fly on and land elsewhere. The difficulty with that is that the flight computer will estimate your fuel burn based on flight level and speed, but not account for the added drag from the landing gear. So what you do then is fly slowly (see below) and land someplace en route, have the gear checked over and the ground pins removed, then continue towards your destination. The mechanic crew would be responsible for (not) removing the ground pins, and the pilots might be responsible for not detecting this pre-flight. But the pilots were both women, so to blame them before any investigation has been concluded is easy in India, isn’t it?
A320 GEAR DOWN SPEEDS
• VLE – 280 / 0.67 (maximum speed with landing gear extended)
• VLO Extension – 250 / 0.60 (maximum speed for landing gear operation)
• VLO Retraction – 220 / 0.54
As long as the auto-thrust is engaged, the A320 aims to stay below VLE when the gear is extended. For gear down ferry flights, the procedure is to switch VMO to 235 kts to protect the gear against fatigue, so if “the plane was also noted to be flying at only 230 knots”, the reason for this could be that the pilots set the appropriate switch for this condition; which would be another indication that these pilots were well aware of the situation and handled it professionally.
P.S.: Airbus has published a 60-page paper on the various speeds that govern the operation of an aircraft at https://safetyfirst.airbus.com/app/themes/mh_newsdesk/pdf/safety_first_special_edition_-_control_your_speed.pdf , it is well worth a read if you’ve ever wondered what all these three letter acronyms mean.