gnetwerker

Perhaps this has been covered before, but I'm curious: I have a long layover in SFO, so I'm sitting by the windows in the UC, looking at Gates 76 and 77 A/B/C. Out of sheer boredom, I've been tracking the tail numbers and other info of the planes coming and going, and I've noticed pretty consistently that the arrival and departure information on both the United app and on FlightAware don't match up with observed reality.

I do understand that "departure" doesn't mean take-off -- it means something like "door closed and brake off", but I've seen a consistent pattern of planes showing as "arrived" while waiting on the taxi area 200 yards from the gate for 15-20 minutes, and in one case (UA5585) an "early" departure was listed a full 35 minutes before the flight actually pulled back from the gate.

That, in turn caused UA5437 (Tail #N785SK) to sit on the apron for a good 15 mins after showing "arrived".

So this may be no big deal, but I was curious.

NH_Clark

I always thought departure was defined as door closed and jetway pulled away. They could sit there doing whatever but it would legally have departed?

RobOnLI

It is all up to the gate agent and when they type it into the computer.

-RM

findark

FlightAware uses runway arrival and departure times once they are filed, whereas the United app will show scheduled until the plane leaves (and uses gate times if the flight is delayed). Not sure whether it then uses gate or runway times for "actual"; can't say I've ever relied on the app since FlightStats shows faster-updated filings of both runway and gate times.

The flight record does keep four times though: gate/runway arrival/departure, and most apps usually choose semi-arbitrarily to use or the other. Things get messy when (to use seasonal regional experience) a flight gets a tentative arrival slot at SFO and a 3-hour delay posts for runway arrival without gate arrival updating. This generally indicates ops doesn't want to publish the delay (it won't show in the United app), and to be fair it sometimes changes.

mduell

FlightAware has both.

jp12687

the app is a joke-- same reason it shows "X" time departure 5minutes after X we are still sitting in the jetway with the door open.

docbert

If you haven't already, check them again now. I've had a few occasions where a flight I've been on waiting for to get to a gate at SFO showed as arrived and a time roughly when we pulled up short of the gate just like you're describing. But then after we actually did get to the gate the time updated to that time.

So yes, the information was wrong for a while, but in the end it's updated to the correct information.

However that's from a very small sample size (twice that I can recall) so I can't really say it's a pattern...

PVDtoDEL

Firstly, UA defines departure as the time when the aircraft starts moving backwards. Most other airlines in the US use the time when the brake is removed.

The app is actually very good at presenting flight status information IMO. Your confusion probably stems from the differences between "Estimated" and "Actual" times and the difference between "Landed" and "Arrived" - the text shows up in the same font and color, but means different things.

fastair

?????? Where did this idea come from ??????

fastair

Sort of....CO defines it that way, UA does the same as most other carriers, at break release with all doors closed. UA is transitioning to the CO way on all aircraft, not sure how far along they are, but most airbi can say "out" still at door closure and break release (so if it is ready for push, but is held by ground controller for traffic,) while the 737s will only show out after a full tire rotation, AFAIK.

sinoflyer

There are two "departure" times and two "arrival" times. The discrepancy can arise when a different criterion is used to indicate departure or arrival.

OUT - either when the brakes are released (PMUA method) or when the front wheel has rotated 1?, 1.5? revolutions on pushback (PMCO).

OFF - Wheels up

ON - Wheels on the ground

IN - brakes applied at the gate

These times are automatically recorded. No agent types nothing into the computer.

suzy1K

This is incorrect. The gate agent has nothing to do with it.
I read this post to a UA pilot. He said its all automated and connected to the plane's braking & landing gear systems. When the pilots release the brakes at the gate it sends a signal to Ops. Another signal is sent when the plane lifts off the ground. That's connected to the landing gear movement (not the brakes). That's called the "off time" ... which then calculates the ETA. Same deal with landing (re: landing gear). When the plane is waiting to be waved in, if the pilots set the brakes that sends an 'arrival' signal. After they get to the gate and re-set the brakes, the arrival time is re-set then re-sent when the door opens.

There are newer computers in some planes that won't send the departure signal until the plane actually moves -- ops can tell that by GPS.

docbert

That would match exactly what I described above - the arrival time IS (incorrectly) shown as the time when the plane pulls up short of the gate, but then is updated when they actually arrive at the gate.

So the UA website/app show the incorrect time whilst the plane is waiting, but the end result is correct.

doobierw

This is incorrect. Our out/in times (departed/arrived) are generated onboard the aircraft and are automatically/immediately uplinked into the flight info system when the trigger event occurs.

Our 'out' time for flight ops (internal metric) occurs when all doors are closed, and the parking brake is released. A separate 'departure' time is generated which is based on when wheel spin first occurs. This is the time that you will see generated as 'departure time' when tracking a flight.

I'm a little less certain when the 'In' (arrival) occurs. It used to be that when a door was opened, the system looked at the time that the parking brake was set for the last time. It either still does it that way, or the 'In' event occurs when the parking brake has been set and a door is opened.....using the actual time the door was opened....not when the parking brake was set. I believe it is the former....not the latter, but not 100% certain of that anymore.

DRW