Recently, there has been plenty of discussion about
engine failures. While recent stories have involved a single engine on an aircraft,
what would happen if all the engines on a passenger jet failed?
If this should happen, all pilots are immediately trained to think “Aviate,
Navigate, Communicate”, in that order. Aviate refers to who’s flying the plane
and what systems need immediate attention, Next, the term “Navigate” refers to the
direction the aircraft needs to go in the moment, and finally,
Communicate refers to speaking with relevant groups, including air traffic
control, other aircraft, cabin crew, passengers, and if time, the company.
A mayday call would also be made over the radio.
There would also be a request to land immediately and have emergency services available. The flight
deck would then inform the cabin crew that there is a quote-unquote “no time available emergency.”
The captain would proceed to ask the first officer to restore the electrical power as soon
as possible. The best way to do this is to start the APU (which is not normally running in flight).
This will restore electrics, but also provide bleed-air for an assisted engine re-start.
The pilot then would then start a shallow glide to the nearest suitable landing spot.
Next, the plane will maintain airspeed by slowly decreasing in altitude. Glide ratio is an
important factor in such an incident. This is the number of feet a glider travels horizontally in
still air for every foot of altitude lost. Here, airplanes use gravity along with their wings and
flaps to keep going as well as the speed that they were moving at before the engines failed.
For instance, if the aircraft has a lift to drag ratio of 10:1, for every ten miles of flight,
it loses one mile of altitude. So, if this plane is seven miles high, it could fly for
70 miles before reaching ground level. A Boeing 747- 200 had a glide ratio of 15:1,
and a Boeing 727 has a ratio of 17:1. Of course, the ratio is subject to factors
like passengers/cargo, along with winds. Captain Chris, a senior Airbus A350 training
captain recently spoke to Simple Flying about the processes on the aircraft that he flies.
“We have a procedure for just about every possibility and if there’s no procedure,
we use airmanship to find the best, safest solution. The A350 is amazing, in the (unlikely)
event of both engines stopping, the aircraft will automatically start the auxiliary power unit, put
the aircraft into a descent and begin Wind-milling start attempts on both engines. Then once the APU
is available, it will provide high pressure bleed air to assist engine starts,” Chris told us.
“Just like a car going down a hill, if the engine stops, it keeps rolling while you attempt to jump
start it. We create the ‘hill’ by descending. Most airliners can glide for about 130 miles.”
A quote-unquote “wind-milling start” uses forward airspeed to spin the large front
fan-blades at a rotational speed sufficient for an engine re-light. However, the speed to achieve
this reduces the glide range. By utilizing the APU bleed air for an engine start, it allows pilots to
select the best lift to drag ratio speed to extend the glide range during engine re-start attempts.
Notably, a real-world example of a dual-engine failure took place in August 2001,
when an Air Transat A330 was flying between Toronto and Lisbon. Flying over the Atlantic,
the plane lost one engine 135 miles out from Lajes Air Base in the Azores.
The other engine then went out approximately 65 miles away.
However, the crew successfully glided to land at Lajes after approximately 20 minutes.
When you step on an aircraft, are you ever concerned about engine failures?
Or is it something that rarely crosses your mind? Let us know in the comments.