What is methodology for reporting departure/arrival times?


#1

What is the methodology used by Flightaware for reporting departure and arrival times? I have seen the terms ‘wheels up’ and ‘wheels down’. Does this mean wheels leaving the runway on takeoff and wheels touching down on the runway on landing, or something else?
I have noticed that different charter and fractional ownership services say they are also using ‘wheels up’ and ‘wheels down’ but the times never seem to agree with flightaware, or with the time I have measured.
Thanks
Mike


#2

Yes, “wheels up” and “wheels down” refers to takeoff and landing. FlightAware roughly uses that methodology as opposed to block to block time. In some cases it can be from radar contact, which would alter the time by a few minutes.

How are you measuring flight times?


#3

Since I am in the plane at the time, I note when the plane lifts off the runway, ‘wheels up’, on departure, and when the plane touches down on the runway, ‘wheels down’, on arrival.
I would like to use Flightaware to cross check the hours I am being charged, but it seems that your methodology isn’t exact because of the variability of data you get from the FAA. The reporting of flight time seems to be the responsibility of the pilots, and they are obviously and appropriately busy during take offs and landings, and I have noticed they don’t always note the wheels up/down times exactly.
From reading other posts, I notice that at times your reported flight time can be several minutes less than the actual wheels up/down flight time because of FAA reporting. True?
Thanks
Mike


#4

Yes – it’s possible. I’d be very interested in any exact examples you had (flight ident, route, your departure/arrival time as noted, FlightAware’s times). Of course, FlightAware’s data & times will be delayed in comparison to your observations. However, they should be accurate after arrival.


#5

DBaker
Here is info on today’s flight, as I timed it. Wheels up at San Jose at 4:03pm, wheels down at Burbank at 5:08. Total flight time of 1:05, confirmed by the pilot.
Tail number N203PT.
This data jives exactly with what is posted on flightaware.com.
Our next flight is this coming Friday, so I’ll post again then.
Mike


#6

You may want to consider your “flight time” may be charged by the time from engine start to shut down-- Taxi can often add 5-10 minutes depending on location. Only charging wheels up to landing would leave out a good chunk of change in fuel cost burned on the taxi. Could this also be a part of the missing time/ overcharge? Are you being charged for the pilots time from when you arrive to the FBO?

Just a thought…


#7

I think most charter operators use some formula like wheels up to wheels down +.1 at either end for taxi. Some might do engine start to engine stop.
I know we’re not talking about a flight school, but if you were…nearly all schools bill by “hobbs” time. “Hobbs” is a name like Xerox copiers, or Scotch tape, it is used even when the meter might not actually be made by the Hobbs company.
Anyway, in some airplanes the meter is running any time the engine is running (by sensing oil pressure), other airplanes the meter runs whenever the Master switch is on, and others, like the pilatus, have a switch on the gear to start/stop the hobbs time. These meters measure in increments of .1 hour, so it’s not always perfectly accurate. If the last renter/student/instructor used the airplane and saw that the dial was just about to roll over to the next number, the considerate thing to do would be to mark that down as your time. (that way when the next guy comes out to the airplane and turns the master on to put the flaps down, the meter has already rolled over to the next tenth, and the guy never even started the airplane…in some airplanes that can be $20 worth of time!)
So, if you use an airplane that just rolled over to the next number, and use it right up to the time where it rolls over to the next number, you could fly for almost 1.2 hours and only be charged for 1.
Likewise, if you get the airplane that is just about to roll over, and fly it right past the next number, you can get screwed for almost 2 tenths of an hour. It usually works out in the wash, so don’t start timing your flights with a stopwatch and bitching about 5 minutes, that’s going to piss off the instructor and/or the office staff…trust me.

Side note… Some airplanes don’t have hobbs meters, but all airplanes have tachometers. The tach meter reads engine RPM, and turns that into “time” on the engine, more like an odometer on the car. It’s different from the hobbs that the hobbs reads how long the engine was running, the tach reads how hard the engine has run. If you idle an engine for an hour it won’t be anywhere near 1 hour on the tach. Likewise, running at full throttle for an hour will be much closer to an hour. In airplanes that have no hobbs meter, or it’s become broken, most schools will use {tach time X 1.2 = flight time}. Again, not an exact science, but it’s been pretty close in my experience.


#8

Well, our flight down to Burbank from San Jose on 4/3 matched the data posted on flightaware.com exactly (as I reported earlier in this thread), but the flight back from Santa Monica to San Jose didn’t match.
The actual wheels up was 3:11pm on 4/6. The actual wheels down was 4:14pm on 4/6, for a flight time of 1:03, which was confirmed by the pilots. Flightware.com shows 3:11pm as the departure time, which agrees with actuals, but it shows a 4:10pm arrival time, for a flight time of 0:59. Flightaware.com shows an arrival that is 4 minutes earlier than actual, and thus also reports a flight time that is 4 minutes shorter. Tail number for reference was N350PT.
Any idea on why this inaccuracy in reporting happens? Again, what I am looking for is a reliable way of verifying actual flight time, wheels up to wheels down, for billing purposes. My service, like most, adds .1 hour at each end to actual flight time for total billing, but it is all based on the actual flight time as they report it.
Thanks
Mike


#9

The FAA sent us an arrival message at 1610, so we mark that time as the arrival time; this appears to be about the time the flight was handed over to the tower, which is not unusual. You can get a better estimate of arrival time by looking at the tracklog. The final position message (300 feet and 110 knots) is at 1613.


#10

Interesting. I understand your comments on the arrival time, but the takeoff is also interesting. I know for a fact that our wheels left the runway at 3:11pm, but the tracklog show us at 2100 ft at 3:11pm. Santa Monica can’t be much higher than sea level, certainly no more than 100-200 feet, so I am more confused. Seems like this is both art and science!

Thanks for the prompt feedback as I learn more.
Mike


#11

So your watch doesnt exactly match every other clock in the world? It might be off 1 or 2 minutes?


#12

This has me curious and I dunno if you can answer.

I would have thought the track log would have ended with the arrival time. What causes the continuation of the flight for three minutes after the arrival time in the example above?

Is there an actual lag where the transponder still gives position reports after the FAA sends the arrival time especially if the pilot doesn’t squawk VFR right away?

Allen


#13

2100ft is only about a minute of climb time for a jet, so if your clock differs from the FAA by 30 seconds and we recieved that position report at 15:11:59 (or anywhere in the latter half of the minute), it’s reasonable to say that both observations are correct. All of the messages we receive come from the national-level ATC systems, so it’s not uncommon to see the first position report when the aircraft is talking to center instead of tower or local departure control.

Since when know the FAA often sends out early arrival messages, we try to continue the tracklog until there is a break in time in the position reports. The code isn’t perfect, but it works in cases like this one.

The flight was still operating with their unique squawk until 1513; a controller had just marked the flight as arrived in the computer.