"Where is this aircraft coming from" questions; Times / aircraft don't make sense!
 

I'm supposed to head to the airport soon and just checked flight status because of the light wet snow we're getting in the Chicago area. My flight shows on-time, but the "where is this aircraft coming from" feature suggests that the aircraft is over 2 hours delayed, still sitting on the ground, and scheduled to arrive 25 min after my scheduled departure time.

How accurate is this feature? Can I be reasonably certain that my flight will be delayed based on that feature, and that there is just a lag in the update to the flight status?

No. Do not trust it at all. Aircraft get swapped in and out of routes all day, every day. Such is the job of the resource managers. Be at the gate minimum 15 minutes prior to scheduled departure - earlier if possible.

My experience is it is not reliable if you check it many hours before your flight. It becomes more reliable the closer you get to your flight time.

I've found it to change many times 'at game time' as the planners do their thing trying to keep planes moving.

It's not that the feature is inaccurate - it's quite accurate in fact - but the assignment of a particular aircraft to a particular flight can be very fluid, especially in bad weather situations.

Great advice and insight! I heard traffic stinks, so looks like I'll be heading out in a few.

As others have noted, plane swaps to alleviate irrops can and do happen, so it just depends how much risk you want to take on versus the free time you'll gain.

That said, UA does tend to be quite bad about updating flight status to reflect delays on the inbound flight (it's really amazing how many times I've gotten to the gate at boarding time, plane isn't even there yet, and still no delay showing), and in cases similar to yours this year I've found myself on the same (delayed) physical plane with only one exception.

I would still get to the airport/gate on-time (especially if your flight is showing on-time). IME, however, the inbound aircraft link is usually accurate especially day of and it is likely that your flight will be delayed. I'm not saying that aircraft swaps don't happen, they do, but I think they are the except rather than the rule. As others have mentioned, more common than an aircraft swap is UA not posting a delay until an hour (or less) before the scheduled departure.

At ORD, you may very well have a plane swap, so it's probably not all that accurate. I've had them swap planes at ORD and SFO frequently--and last time it happened at SFO, I suspect they had a lot of "no shows" since there was no announcement at the original gate, the flight moved up to almost back on schedule (vs. 3 hours delayed), and changed gates significantly.

I've also had many flights say "on time" up until 10 minutes after scheduled departure when the inbound flight was still in the air.

It's been VERY bad in the past, but United has slowly been improving it. Unfortunately though, it can be VERY hit or miss, so be careful. If it's a small airport, you can pretty much trust the status departure time, but if it's a hub, they'll change equipment on you and you may miss your flight.

That's pretty much the rule I follow.

Exactly! If you are at a non-hub, in general it is extremely accurate. If you are at a hub, depending on how late the flight is supposed to be, they may do their best to substitute.

Let's put it this way, I trust it enough to stay in the bar for another beer but don't trust it enough NOT to get to the airport.

Sagely advice.

I had a flight earlier this year change tail numbers about 4 times at EWR. So yeah, they are very proactive trying to get flights out when/where possible.

Especially at a hub, where there are other planes that can be prioritized, it's a good thing if you ask me - anything to get the flight off the ground!

Just to close the loop on this, I arrived at the airport 30 min ahead of scheduled departure and found that it had been pushed back 30 minutes, so still good on time. Also switched to a different aircraft which had been sitting around all day, as the originally scheduled aircraft was several hours delayed. So definitely good advice from everyone.

Down side is that our plane was delayed getting to the gate b/c the outbound occupying the gate was delayed departing, then we had de-icing issues, and eventually pushed back 3 hours late. :(

My experience at EWR - depends on carrier. If UA plane & crew don't trust it as they will swap out planes, gates last minute and you leave early.

If a regional partner/carrier - the information is accurate and UA (5xxx+) will show On-Time even if the inbound aircraft is 3 hrs from departure. It is a struggle to convince UA of the aircraft delay to reroute you so good luck.

Just like the flight status feature, the inbound aircraft feature is accurate. But, only at the moment you are viewing it.

Especially at ORD and with lousy WX, there may well be last second swaps, so it means nothing that a given aircraft is scheduled to fly a given route.

Remember, if you are not at the gate by T-15 of scheduled departure, you may lose your seat and this is especially true in IRROPS when seats may be needed. Even if your flight is delayed, that does not mean that you may delay your gate arrival.

Just this week flying out of PDX the metal was shown as sitting in SEA 3+ hours delayed, but gate screen showed on time departure. I asked the GA who told me they were pulling a new plane from the hangar for my flight. We actually left early!

GA was surprised I knew our original metal was still in SEA - she didn't know the UA website showed that info.