Flight Arrival Times - how accurate?

[newswatcher]

Newswatcher offspring due back from holiday yesterday morning. Thomson flight due Gatwick 04:45hrs. Drive to airport takes about 1hr., plan to leave about 4AM.

At 3AM, flight showing as expected on CEEFAX at 04:12hrs. Quick update to plans, and arrived Gatwick at 4.20AM. However, arrival time shown on airport screens now 04:35hrs.

How does flight add nearly half hour over one hour duration? Airport information say times received directly from airline.
:confused:

Daughter eventually appears at 5.40AM. Not best pleased with speed of baggage handling either!
:mad:

[BRUpax]

Sounds a lot better than your trains though :} ;)

[Globaliser]

Depends on how "real time" the information is, I suspect, and how often the airline updates each channel. There may also be some confusion if some channels give the expected "on" time and others give the expected "in" time - comparing the BA and BAA websites for BA flights is always a good recipe for confusion over that.

The more interesting question in my mind is this: If you've just been on holiday for a week, and you return on a flight that arrives at LGW at 0445, and a parent has to watch the TV at 0300 and leave the house at 0400 to collect you - isn't this just a self-perpetuating business on the part of the holiday company, as they've now caused two people to need another holiday? :D

[newswatcher]

globaliser, there was certainly some discussion at the Information desk as to the difference between "expected time" and "estimated time". In this case I'm pretty sure CEEFAX showed "expected". It's just a pity that these times cannot be relied on.

As to your second point, it does look a little indulgent, but then it's reciprocal, and my wife and I can look forward to being picked-up at anti-social hours when we go away!

:ok:

[Whispering Giant]

Newswatcher - a slight correction to what you have been told by airport information.
The times provided come mainly from ATC - the departing station sends a movement signal once the flight has departed which will give a estimate based on a scheduled block time for the flight.
This information is then further updated at the destination airport by ATC based on the aircraft's groundspeed en-route if there's any weather to contend with on the route and finally how busy the airport is when the a/c is expected to arrive and if any allowance for holding is necessary.
hope this explains it for you.

brgds
W.G

[Lost_luggage34]

In the good old days, the BA system fed a link to Ceefax (or Oracle in those days) every 5 minutes. Little better than a piece of wet string!! but it seemed to do its job most of the time.

The BA system took its info from the BAA system which in turn came from ATC, adding 10 minutes to the 'finals' time to provide a 'landed' time.

This arrangement obviously had no compensatory factor for go-arounds etc. That was how it worked at LHR and I imagine similar at LGW.

One would like to think it has been updated somewhat these days as I am merely providing an historical description.

[Globaliser]

Lost_luggage34: One would like to think it has been updated somewhat these days as I am merely providing an historical description.The BA website now takes a direct feed from the ops system, as far as I can tell. Mobile phones, of course, now provide a check on this.

The last time that I was inadvertently checking it, I was on the phone to my partner who was on a delayed flight waiting to push back at LHR. I was refreshing the BA website screen from time to time to see whether there was any updated information coming from that.

Suddenly, somewhat earlier than the BA website estimated time, my partner said, "I have to switch off now because we've just started moving" (with engine start to come next). I pressed refresh and the screen immediately displayed the current time as the "departed" time. :ok:

[jabird]

Globaliser,

And you could add that being too precise with the estimates would mean a big loss in airport parking revenue. Profits on those 36 minute stays must offer some of the best space utilisation in the business.

It does surprise me though that some airports (eg BHX) are not so quick on providing more refreshment stands around the arrivals hall. Not to mention an on-airport travel agent, and some screens to advertise the latest flight specials.

[Maude Charlee]

The airport information desk at my local (regional) airport gets its estimated times from the ground handling companies and not ATC. The handlers are copied in on all relevant movement messages from the departure airports and the information desk is subsequently updated as necessary.

However, messages may contain estimated departure times as the aircraft is expected to depart late, and therefore any time passed to the information desk is purely provisional. Even when the aircraft has actually departed, times may contain 2 errors.

Firstly, many ground handlers fiddle departure times to try to maintain an illusion of on-time performance when in reality the aircraft departed late (if all aircraft are ever fited with ACARS this might no longer be a problem, but you'll see O'Leary join the clergy before that happens). Obviously arrival times at the destination will reflect this innacuracy, with the aircraft arriving later than estimated.

Secondly, the arrival time is also based on the aircraft flight time. Again, not all ground handling agencies provide an accurate flight time, or use flight times based upon older and less capable aircraft (easyjet for example still has flight times for many routes based upon the 300 series 737 and not the more capable 700 and aircraft routinely arrive well ahead of schedule). If flight times are little more than guesswork, then clearly arrival times are going to be a work of fiction too.

I can assure you that it is not just the public that find this frustrating. It plays havoc with operational planning too.

[Curious Pax]

Don't know if it still happens, but when I was a despatcher a couple of decades ago there used to be an estimate based on the departure time from home base (for UK based aircraft), which was updated when they arrived at the far end, then again once they got airborne on the return leg, and finally when the crew gave the handling agent a call usually about 20 minutes out when they would have a good idea of the real eta. For Manchester I suspect that is still the case, as the eta often changes about 20 minutes before arrival (though not normally by too much). Not a problem for me as I only live 15 minutes away, but can see it would be a nuisance for those from farther afield.