What Happens When Aircraft Run Out Of Fuel?

Think an aircraft can’t run out of fuel? It can, and it did! And the outcome might surprise you…

Air Transat Flight 236

Air Transat flight 236 was flying from Toronto, Canada to Lisbon, Portugal.

The twin-engined A330 was crossing the Atlantic about 3 hours into the flight when, unknown to the crew, the aircraft started to leak fuel.

The crew received a warning about the engine (caused by the fuel leak), which they considered to be spurious (or false).

The fuel continued to leak and then pilots received an ECAM (Electronic Centralized Aircraft Monitor) warning of a fuel imbalance between the wings.

Airbus ECAM System Display - Fuel
ECAM Fuel Page on Airbus A330

Still unaware of the fuel leak from the right hand wing, the pilots tried to balance the fuel load but actually made the situation worse.

Aware they had a serious problem they declared a MAYDAY and pointed their jet towards the Azores Islands in the Atlantic Ocean.

During the diversion both engines flamed out due to the lack of fuel.

Related: Airbus Green Dot Speed

The loss of both engines meant the pilots were left in a dark aircraft with limited control due to the resultant loss of hydraulic power.

A backup emergency system called the “RAT” (Ram Air Turbine) deployed which gave them enough power to control of the aircraft.

Related: A Guide to the A330 Hydraulics System

Without engines the pilots had to glide the aircraft towards the island. They succeeded and all 306 passengers and crew were saved.

Despite being criticised later for errors made in their procedures, what the pilots achieved was amazing. Gliding an A330 for a safe landing in the middle of the Atlantic.

Despite the skill of the crew, it would have been a different outcome without the miracle RAT – more info about that system can be found here:

Related: The Ram Air Turbine (RAT) Explained

The Gimli Glider – A Metric Mistake

In 1983, Air Canada Flight 143 from Montreal to Edmonton was planned on a Boeing 767.

The pilots were aware from reviewing the aircraft’s Tech Log that the aircraft’s fuel gauge were INOP (inoperative). Despite dispatch not being allowed with blank fuel gauges, the captain mistakenly believed the aircraft could be dispatched legally in accordance with the MEL, or Minimum Equipment List.

The aircraft was refuelled in Montreal but due to an erroroneous use of pounds instead of kilograms the pilots were told 20,400 KG on board when in fact they had less than half that amount.

This mistake was unknown to the crew at the time and they entered the fuel load that they expected to have into the FMS, rather than what they actually had. This meant the FMS predicted sufficient fuel for the flight when in reality there was only 9,144 KG.

During cruise at 41,000 feet the crew received the first in a series of EICAS (Engine Indicating and Crew Alerting System) warnings: a problem with fuel pressure in the lefthand tank.

Aware that the engines can be supplied by fuel by gravity alone, and suspecting an issue with only one fuel pump, they turned it that pump.

Moments later the crew received the same warning, but this time for the right wing. Aware there was a serious problem the crew began a diversion and turned the aircraft towards Winnipeg. Short afterwards, starved of fuel, Engine Number 1 wound down.

Shortly afterwards, Engine Number 2 also shut down.

Without the electricity generated by the engines the crew were left with blanks screens and only a few backup instruments that were running on battery power. The Auxiliary Power Unit was not available due of the lack of fuel.

The Captain was an experienced glider pilot (as was the case with Air Transat 236) and based on the glide ratio of the aircraft he knew they would never make it to Winnipeg.

The First Officer had been in the military and had been based at RCAF Station Gimli. It was closer than Winnipeg and though they knew it was closed it was the best option they had. What they didn’t know, however, was that part of the base had been converted into a car racing strip, and there was a race taking place at that time!

Due to the design of the landing gear system, the gear had to be lowered by gravity, but the nose wheel did not lock down.

Without power the crew had been relying on the Ram Air Turbine (or RAT) to supply hydraulic power to the controls. As they began slowing for the approach the aircraft became much harder to control (the RAT on the B767 supplies adequate hydraulic power at speeds above 130 knots).

As the aircraft was gliding and not making any noise it was only at the last minute that people say the Boeing 767 coming in to land.

The nose wheel collapsed on landing but the captain managed to stop the aircraft without injuring anyone on board or any of the spectators on the ground.

The only minor injuries were from passengers evacuating from the rear doors which were higher that would normally be expected, and the slides didn’t reach the ground.

The pilots had to get the approach right. There was no second chance – there was no possibility of a go-around.

Considering that 17 minutes after losing both engines, they were on the ground and everyone was safe was almost miraculous. I say almost because it was really the skill of the pilots that saved everyone that day.

Here is a great article about the incident: Flight Safety Australia “The 156-tonne Gimli Glider”

Avianca Flight 52

Another aircraft that ran out of fuel was Avianca Flight 52 in 1990. Unfortunately the outcome of this flight was very different.

Avianca Flight 52 was a scheduled flight from Medellin, Columbia to New York JFK airport. On the previous flight the crew noticed issued with the autopilot and as such the to JEK dispatched in accordance with the MEL (Minimum Equipment List) with the autopilot considered INOP (inoperative).

The aircraft dispatcher had ordered the maximum amount of fuel which would have brought the aircraft up to it MTOW, or Maximum Take Off Weight. The captain requested a different departure runway which allowed the flight to dispatch with more fuel.

The first part of the cruise proceed without incident. Approaching Norfolk, Virginia the crew were instructed to enter a holding pattern – the first of three holding instructions they would receive.

The second hold was in the area of Atlantic City, New Jersey and the final hold the crew entered was on the arrival into Kennedy. It was at this hold that the crew were informed by Air Traffic Control of an “indefinite hold” and to expect further clearance in 20 more minutes. The crew had already been given two delay estimates which had since passed.

It was at this point that the crew began to voice concern saying that they could hold for only 5 more minutes – they requested “priority”.

When asked which airport was their alternate they said it was Boston, but now they did not have the fuel to make it there. A fatal mistake.

ATC began to issue the aircraft vectors for the ILS 22 Left at Kennedy. During the approach (hand flown due to the autopilot being INOP, and in bad weather) the captain deviated below the glideslope enough to receive a series of GPWS (Ground Proximity Warning System) warnings. Disregarding the warnings (which became more serious) the crew pressed on but could not see the runway and executed a missed approach, climbing away again.

The first officer informed ATC that they were “running out fuel” a number of times.

Nine minutes after going around the engines flamed out and the aircraft crashed northeast of JFK with the loss of 73 lives.

The crew communicated with ATC using terms such a request for “priority” and saying that they were “running out of fuel” but at no time did they declare a “Fuel Emergency”, PAN-PAN or MAYDAY which would have made them the highest priority aircraft.

They didn’t have a “bottom line” in terms of the fuel they had on board – they allowed the situation to develop where they didn’t enough fuel to reach their alternate and they couldn’t land at their destination.

Although its easy to second guess the events that lead up to the tragedy the accident report cited poor communication by the crew and poor management of their fuel.

NTSB: Avianca Flight 52 Accident Report

What have we learned?

Although nothing can bring back lives lost the one positive thing to come out of these and other accidents are the lessons the aviation industry has learned.

These days communication standards are more robust. Crosschecks and independent verification are normal.

In the case of Air Transat 236 airline SOPs (Standard Operating Procedures) were changed. The Quick Reference Handbook (QRH) and other systems were changed by the manufacturer. Crews have learned that in the case of a fuel loss, even a case of suspected fuel loss, the priority has to be to land the aircraft ASAP while minimising the fuel loss.

A captain told me before that he would be extremely reluctant to open the “Fuel Cross Feed” in flight (this is a system that in a way connects the tanks in both wings). We do have procedures (for example, for fuel imbalance) that call for the Cross Feed (or “X FEED”) to be opened but I would be very hesitant to do that.

The A330 QRH procedure for Fuel Imbalance now states very clearly at the top:

“A fuel imbalance may indicate a fuel leak. Do not apply this procedure if a fuel leak is suspected”

Had the crew of Flight 236 left the cross feed closed they would have had an engine failure – but only one.

And as regards Avianca Flight 52 there were many contributing factors but what was highlighted in the accident report was that, due to their reluctance to declare a MAYDAY, air traffic control didn’t understand the peril they were in.

These days there is very clear guidelines on what to say and when to say it. There is an emphasis on training both on the ATC side and from the point of view of the pilots.

As I say, nothing can bring back the people that were lost, but I believe the lessons learned in these tragedies have saved other lives.

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