Maybe you were surprised, before a landing, to hear the pilot or the crew asking to turn off all cell phones, tablets and computers. However, it is enough that the devices are in airplane mode, so what’s wrong with them asking for a complete switch-off?
Well, the answer is simple: you will make an automatic landing(or “autoland“). In other words, the plane will land without the pilot’s intervention (except that his PRESENCE is fundamental, as you will see later) and this requires the application of certain precautions, among which the total extinction of all electronic devices.
Autoland for blind landings
When cruising, pilots use autopilot. All they have to do is give the plane a speed, altitude and heading and the autopilot takes care of the rest. But some aircraftcan also land “automatically” under certain conditions.
This is a procedure used when visibility is insufficient for a “conventional” landing.
It is therefore appropriate to begin by asking how to land a plane:
Visual landing, instrument landing, automatic landing
Historically, the first known form of landing is the visual landing. The pilot sees the runway and lands his plane. This is how it was done in the early days of aviation. A viable approach at the time when we flew less high and where the imperatives of commercial aviation did not require that one can land at night or regardless of the weather (well in fact before being commercial the need was, as you can imagine, military).
So the industry has been working in two directions: blind landing and automation.
Blind landings are based on the Instrument Landing System or ILS. A beacon indicates to the aircraft the direction of the runway, another the angle it must follow to land. By visualizing these indications, the pilot can bring his aircraft to the runway almost blindly. An instrument landing is called an IFR landing (Instrument Flight Rules).
Once the information for an IFR landing was available, all that was left to do was to automate the aircraft’s actions accordingly. And this is nothing new. Instrument flight dates from 1929, the first instrument landing from 1930 and the first automatic landing from 1937 for military aviation. The first ILS was installed in 1932! Of course it has been perfected over time to reach today an extreme precision. The first fully automatic landing without pilot intervention for a commercial aircraft dates from 1960: it was an Air Inter Caravelle.
In practice, pilots only use the automatic landing in really extreme cases. In general they fly with instruments and in automatic up to a certain altitude called “decision altitude”. If, after reaching this altitude, they see the runway, they take over the controls and perform the landing manually. If they don’t see it, they stop their approach and go around.
But under certain conditions, the aircraft can go all the way to the end of the maneuver and land by itself without the pilot’s intervention if the pilot, once at 50 feet from the ground, engages the appropriate system.
An aircraft can land without pilot intervention if…
Unsurprisingly, there are restrictions to the automatic landing and they concern the pilot, the aircraft and the runway.
The pilot, of course, must be trained to do this. Without going into too much detail, some ILS allow it and others do not (CAT I and II ILS allow to bring the aircraft close to the ground, CAT IIIb to bring it to the ground). Finally, the aircraft must be certified for, which means two things First of all, and this goes without saying, to be “intrinsically” capable of doing it. Then to have recently demonstrated that the systems allowing autoland work. To be certified, an aircraft must have performed at least one autoland in the last 30 days, which explains why autoland is used even in the middle of summer when visibility is at its best, in order to maintain the qualification.
Yes, but why do I have to turn off my cell phone in case of autoland?
Oh yes, we have moved away from the original subject. Indeed since 2014 you can use your mobile during all phases of the flight, even if it remains at the discretion of the airline. However, the total absence of impact of the devices, even in standby mode, has never been demonstrated at 100%, the risk of incident being simply estimated as highly unlikely. But in case of autoland, it is considered that the conditions are critical enough to impose that all the devices are totally switched off and not only in airplane mode. This includes laptops. A kind of precautionary principle.
A poorly followed instruction?
One question I’ve often asked myself is “will people really turn off all their devices?”. According to my recent experiences the answer is “no”.
In the first case, the pilot announced the fact that we were going to land automatically and that this implied turning off all the devices. It seems to me that most of the phones around me have been turned off but I haven’t seen anyone take out their computer to turn it off. On the other hand, many passengers talked about autoland among themselves and, obviously, those less used to air travel were a bit apprehensive.
In the second case the only announcement was “due to the lack of visibility we ask you to turn off your electronic devices”. The link between visibility and electronic devices being far from obvious, I can tell you that apart from those who knew what it meant, nobody moved.
This raises the question, moreover, of the mode of announcement. Announce the automatic landing to educate even if it will worry some people or just ask for the switch-off without anyone understanding why?
The reason is simple: the transmitting power of today’s phones on multiple bands, 3G, 4G, Bluetooth, Wifi, a good portion of the seats being very much in range of the complex electronic boxes under the floor towards the front of the plane.
By the way, does the aircraft really land without pilot intervention?
Well, while we’re at it, we might as well ask the killer question. Could we totally do without a pilot if he does nothing during an autoland?
If the aircraft lands alone, it does so under the supervision of the pilot, which is not the same thing at all.
The aircraft, for example, will not decide on a go-around, that is the role of the pilot.
At 50 feet it is the pilot who decides to continue in automatic until the end, not the machine.
The aircraft will not engage the thrust reversers alone, nor will it be able to drive the aircraft from the runway to the terminal on the taxiway (at least for now).
And to thank you for reaching the end of the article, the video of the landing of an Air France Airbus A330 at Roissy in automatic mode.
https://www.youtube.com/watch?v=i1joEc-vKsk
And that of a Boeing 737 in Geneva.
PS: I have tried to be as accessible as possible to the general public, so experts should forgive shortcuts or approximations. And thanks to my dear “Triple T”, long haul pilot, for having reread, brought some precisions and validated that the “earthling” that I am was not talking nonsense.
Photo : swithc off cell phone by asiandelight via Shutterstock
Articles similaires
