Questions about flight durations / information

[Nicholas49]

Hello

I have a couple of questions about the duration of flights, if I may. As usual, this is only to satisfy my curiosity!

1) Pilots often tell the passengers how long the flight will take. A captain on a flight I took said the flight (London Stansted to Rome Ciampino) would take 'in the region of 2 hours, 27 minutes'. I understand that the FMC provides very accurate flight time information, and that he was able to be so specific as a result (the passenger next to me quipped dryly 'so, not two and half hours then'), but what I want to ask is: is this the time from push-back to arrival on stand or from take-off to landing?

2) When the arrivals board shows, for example, 'Expected 11:08', is this the touch-down time?

3) I appreciate it's an estimate, but how are such specific times calculated when there are any number of variables (e.g. not knowing at FL380 that you will have to hold for fifteen minutes; the pilot may request extra track miles to comply with stable approach SOPs etc.) which affect the flight's duration?

4) Where are the estimated arrival times shown on the arrival board sourced from? Are they taken directly from the aircraft or from EUROCONTROL (in case of European flights)?

Thanks for your help.
Nick

[Piltdown Man]

1. If I say flying time, I mean flying time. I'll also inform people of the expected taxy time and/or the time on stand. This way everyone should have a reasonable idea of where we are and more importantly, our ETA. So those with connections will know where they stand and those leaving the airport at the destination will, if they are quick, be able to arrange a pick-up. Also for me, 2hrs 27 mins is "about two and a half hours" or I'll even say the "The flight plan says 2hrs 27minutes but I expect we'll be able to shave a few minutes of that so it will be nearer 2 hrs 20".

2. Hopefully the handling agent will put the time at gate on the arrivals board but I think you'll find everywhere is different. But for Heathrow though, any ETA for the stand is purely guesswork as it can take upwards of 40 minutes to taxy to your stand so a landing time would be more appropriate.

3. The flight plan should allow for the expected route (with the likely runways), the weight for the plane, the temperature, winds aloft (climb, cruise and descent) plus taxy time at both ends. I would not expect it to allow for a hold nor any extra track miles (as doing so is a complete waste of time any money - descending earlier is a better technique). However, route and regional experience should allow you to guess a reasonable 'fudge' factor to modify the plan.

4. The times you see first thing in the morning on the Arrivals Board is normally the scheduled arrival time. As the day unfolds reality gets in the way of the plan and changes may be then reflected on the board. Then, when airborne, a departure message is sent to the inbound station which will contain the flight plan's expected elapsed time (EET) from which the landing time can be calculated. This will then be passed on by the handling agent. Then, as some aircraft get closer to the destination (say within 45 minutes), the aircraft transmits its own calculated ETA and this may also be used to update the Arrivals Board.

But overall, the (live) flight information exists - it's just a matter of getting ten parties or so to pass on and publish what they know. It's easier said than done.

PM

[Di_Vosh]

In my airline (regional Oz) our sector lengths are typically 75 minutes or less. We have an expected flight time based on forecast winds. All worked out on paper but gives a reasonably accurate (within 3 min) answer.

Our FMS is a little on the primitive side and when we're giving our first pilots PA we're in the climb (FMS is giving us our arrival time based on our current speed).

If going to an outport we give our passengers the expected disembarkation time. If going to an international airport, we give the landing time followed by "disembarking around five minutes later at...". Going to an international airport we also generally make a "subject to Air Traffic Control" as we can be given a delay time of up to 30 min (on a 60 min flying sector :eek:) in the cruise.

For info, in Oz the "sector time" is generally given as "wheels moving to wheels stopped".

Hope this helps,

DIVOSH!