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You certainly all know that it is forbidden to use cell phones on board planes. Let’s talk about that, as this is something some people find frustrating, let’s have a look at that. This is a particularly hot topic as some airlines (including Air France) are now allowing this, via their own antenna on board.

As a cell-phone owner, you probably already noticed that when you put it beside a radio or a tv, when someone’s calling you, the tv / radio speakers are disturbed and emitt loud cracks. But as soon as you get your cell-phone away, the cracks diminish quickly.

These cracks come from the interference between your sound system and the microwave-like waves used by the cell phone technology. In a plane, the same could occur. And as the plane antenna are dispatched under the fuselage at various places, a cell-phone could potentially generate the same cracks in the radio used by pilots to communicate with air-traffic control, or for with the radio-navigation system.

From a technical point of view, the probability is extremely remote, but hey, would you like to take a chance ? Imagine for a second that your phone creates an interference with the instrument landing receiver while the plane is following its signal, 30 meters above groud, and give then an incorrect indication to the autopilot. This phone call could have been delayed… no ?

So the easiest is to switch off your phone while boarding the plane. You will then avoid dancing while seated to find it in your pockets, and have a longer “phone off relaxation” time.

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Category: On Airports and Airlines

One important thing when talking about aerodynamics is that the speed which is relevant in lift generation is the relative speed between air and wing. Speed relatively to ground has no influence, except for take-off and landing.

If wind is blowing, planes will take-off and land in opposite direction, so for the same air speed (needed to generate lift) the ground speed will be less, so the ground roll will be shorter, and more controllable.

The problem with wind start when they are fluctuating. If there is a sudden change in wind speed during an approach (what is called a “windshear”), the relative airspeed could be significantly changed, leading to potentailly strong changes in lift, then in vertical speed.

By chance, modern airliners have computers that know the airspeed from airspeed sensors, and groundspeed from GPS, so they can detect any windshear and notify them to pilots. The only “cure” is just to apply full power, and go arround for a second approach.

The other major issue with wind is when it is not blowing parallel to the runway. As the plane is moving relatively to air, the only way to maintain a straight ground track (needed for landing, isn’it ?) is to fly with the nose in the wind direction, flying in a “crabby” fashion.

This is perfectly ok to maintain a trajectory relatively to ground, but raises an issue, as the landing gear are not orientable, so immediately before (in some case after…) landing, the plane must be put in line with the runway.

Some examples of this technique are shows in the following video. Please understand that clearly, what you will see is indeed very good pilot skills, not bloody pilots missing their landings.

The next video is from a simulator (no airline will ever allow its pilots to even try such an approach), but it is very good for demonstration, as it shows the same approach from outsite and inside the planes, with angles that would be impossible to shoot from in reality.

The next time you will have a firm landing in crosswind conditions, or a go arround, please remind that this is how to do. And a go arround is never a bad option.

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Category: On Airports and Airlines

These questions look silly to you, don’t they ?

You would then be surprised by the number of pilots who approached and / or landing to a wrong runway, a taxiway, a runway at an other airport, or a nearby bridge or motorway.

This could look silly, but it’s not always so obvious to identify a runway when taxing at night, especially when it’s raining and light is creating tons of reflections…

One business jet pilot once told me about a taxi clearance he got from Brussells ground controller after vacating the runway… it involved about 10 different taxiways !!

One of the latest avionics development concerns runway incursion warning system, based on GPS signals which are accurate enough to know if the place is on a runway or a taxiway.

There is a urban legend about this in Frankfurt, where the controllers are known to be expecting pilots to taxi from runway to their gate on their own, which is quite hard on such a complex airport. The story tells that a british pilot, who converted to airline pilot after world war II did land there… the following dialog then took place:
Controller: Speedbird 1234, taxi to gate 45 via standard taxi route
Speedbird 1234: Sorry Sir, we’re not familliar with the airport, request detailled taxi clearance.
Controller (a bit pissy): Speedbird 1234, did you never come to Frankfurt before ?
Speedbird 1234 (with british flegm): Yes Sir, I did, but did not stop and dropped things over
The legend don’t says anything about the controller’s answer.

You may be noticed big number painted on runways, to identify them. These come from runway angle with respect to magnetic north, rounded by 10 degrees. So a runway 23 has a magnetical orientation between 225 and 235 degrees. This is also why the numbers at each end are different, and always different by 18 !

So, what about parallel runways ? Dialog between pilot and controller must be unambiguous. When an airport has several parallel runways, they are then designated by their number, followed by L (left) or R (right). So if an airport has two runway with an orientation of 70° with respect to magnetic north, they will be 07L and 07R, and in the other direction 25R and 07L respectively.

Final trick, if an airport has 3 parallel runways, the center one will be designated 07C (center).

One note before I stop this already too long post (I told you I’m passionated about that). To be able to operate runways completely independently, that is to be sure there is no influence of traffic on one regarding traffic to the other, their centerlines must be 700 meters apart.

PS: if you see in a movie with Leo Di Caprio and Tom Hanks (Catch me if you can) a plane being cleared to land on runway 59, you’ll know that it’s not correct !

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Category: Flying Tips