Who has final decision to land?

[weegsltl]

Hello,

Myself and some friends have been having a discussion about who has the final decision to land - the pilot or ATC.

For example a pilot is making an approach to an airport and ATC informs the pilot that in their opinion the runway is not long enough to land, however the pilot has done his calculations and is happy that they can safely get in.

Would the pilot then have to choose another airport or pass the information he had on why he could land and ignore ATC. I have read that ATC provide a recommendary service and therefore (although you would be silly to do so) you can accept all responsibility and ignore ATC instructions.

On a side note to this would Hawarden Airport (EGNR) be able to accept a 777 (as this is where the discussion comes from). Offical facts show that a light 777 could operate into and out of NR, and a real world airline (that operates 777 and 747s) says that any of its fleet could operate into NR. However my friend states that a RW controller there says its impossible to land anything bigger than a 767. Therefore some input into whether this would be possible would be appriciated as well.

Thanks

[eyeinthesky]

Under Public Transport rules, there are strict and clear calculations which you must make with regard to how long a runway needs to be. They revolve around the need to cope with an emergency such as an engine failure.

Having started your take off run, you need to be able to stop, without damaging the aircraft, within the runway length plus any stopway at any speed up to V1. (V1 is the maximum Indicated Air Speed you can reach and still be able to stop in the remaining distance). Beyond V1 you are committed to continuing to rotate speed (VR), (even if an engine fails) and a subsequent take off and there are rules about obstacle clearance following an engine failure. VR is a speed governed by the weight of the aircraft and its flap setting, not the length of the runway. The lighter the aircraft the less lift the wings need to provide and VR will be slower on a lighter aircraft.

So, there is a gap between V1 and VR. The size of this gap is also regulated for obvious reasons. Say you decide that you can get to 80 kts and still stop by the end of the runway but that you cannot rotate until 120 kts, there is a 40-kt no-mans land when you can't stop but you can't fly either. This is not a good idea!

What all this means is that it all depends upon runway lengths (or, more correctly, Take Off Distance Available-TODA) and aircraft weight. So arguably it is perfectly possible for a light 777 to take off from Hawarden given the right criteria. Only someone with the performance charts for the aircraft could give you a definitive answer. Don't forget Air Force One B747 departed Teesside (2291m) for the US direct the other day. The TOW for a B747 was probably quite light and I'm sure they wouldn't risk it if it wasn't within limits!

In all of this, I have only considered the take-off scenario. There are also limitations on landing. But there is no point in landing at an airfield which you can't then take off from (unless you happen to be flying Concorde last week.. :{ :(

With regard to your main question: It is the Captain's ultimate decision. All an ATCO is do is give the relevant warnings but you cannot physically stop them landing. They can expect lots of paperwork, or worse, to follow, however! There have been a few cases of pilots landing when the RVR was below airfield minima, and all the ATCO could do was advise them of that fact and request their intentions, followed by: "There is no known traffic to affect your landing". The crews involved had a lot of explaining to do to the CAA!

[bagpuss lives]

We had a PIA 747 land after being instructed to "go around" some weeks ago at Manchester. There's a lively debate all about it here :

http://www.pprune.org/forums/showthread.php?s=&threadid=100216&highlight=PIA

[FWA NATCA]

How can ATC tell you the pilot that the runway that you intend to land on is not long enough? ATC (the controllers) are not crunching the numbers to determine what length that you need or don't need to land or takeoff.

Now if there is a maximum weight limit established for a particular runway then ATC can deny a landing or takeoff clearance for your particular aircraft, but in the example that you gave, NO, unless the rules in the UK are vastly different than the USA.

Mike

[vintage ATCO]

ATC can only withold clearances for traffic reasons. Over and above that they can warn you that, in their opinion, something you intend to do is potentially dangerous or contrary to the ANO, and then simply say "There is no traffic reason to affect you . . . ."

However, bear in mind that ATC may be passing on instructions from the aerodrome authority and they, without getting into a debate about ordinary and public aerodrome licences, can have a bigger say on who does what to their aerodrome. ATC should state if it is passing on such instructions.

All this is a bit academic. Any airline thinking of flying a B777 anywhere would have done the number crunching before turning up, unless it is a completely unexpected diversion.

We have B777s into Luton and they will often take an intersection departure rather than the backtrack.

[weegsltl]

Thanks a lot chaps,

Helped me a lot - cheers!