2 flights on same day with same flight number at LHR - unexpected consequence
 

The purpose of this post is to detail an unexpected consequence when Flight AC868 (the only daytime flight YYZ-LHR) was seriously delayed on 23 Aug. A similar situation could happen again, so be warned.

Instead of leaving at 09.10 on Wednesday, it was delayed to 23.45 (reason not relevant here). So, instead of arriving at LHR on Wednesday evening, it arrived on Thursday at approximately 11.40. We had rescheduled our transfer from LHR, on the basis of the flight number and an estimate of the arrival time.

The normal process is that the transfer company monitors the flight arrivals. However, the rescheduled AC868 did not show. They found AC858 arriving at 11.00, assumed we had made a mistake, and so sent the car for then.

My daughter, living in London, was in contact with the transfer company, and had set up the transfer. She called Air Canada in the UK. The agent insisted that AC868 arrived at 21.00 (the Thursday flight) and knew nothing about the Wednesday delayed flight. The agent was quite rude about it, and seemed to think the caller was an idiot. As were in the air, we knew nothing about all this. When we failed to come out from AC858, she managed to persuade the transfer company to wait longer, so they still were there when we arrived. If she had not been involved we would have been really messed up, as we had an outsized piece of baggage, requiring more than a regular taxi.

The baggage carousel at LHR showed our flight number as AC868 followed by a letter. It did not show on the arrivals board - I am guessing that 2 flights with the same flight number arriving at LHR on Thursday upset their systems. YYZ was not messed up as Wednesday's departure was still (just) on Wednesday.

I have experienced a similar situation when a LHR-YUL flight was delayed from the afternoon to the next morning. In that case the rescheduled flight had a new flight number so LHR and YUL did not have to deal with 2 identically numbered flights on the same day (and we got 600 Euro compensation as it was from the EU - unlike flights from Canada).

I really do wonder how some people have a job

Bilingual people can get jobs in federal politics, Parks Canada, and Air Canada. And there aren't that many to go around.

Very likely that the agent had no infor regarding the delayed flight. Wednesday's "AC868" was likely not in the system since a new flight number was assigned.

There was no new flight number assigned for my YYZ-LHR flight. It left YYZ at 23.45 instead of 09.10 on the same day. But LHR had 2 arriving the next day with the same flight no. Anyway, my daughter explained that the flight she was trying to find out about was the previous days departure.

My reference to a new flight number referred to a similar delay LHR-YUL a few years ago. That time a new flight number was assigned. Maybe that is what AC should have done this time - but they didn't.

Something like AC868A is considered a new flight number, that's why you saw it in the baggage claim area, and likely that's why the phone agent could not find "AC868".

Flight numbers like AC2068 are usually used for flights with delayed departure till next day.

The problem is, the flight number update was not done correctly in the system.

The problem is "the system" was designed when it was a support system for 32 smart individuals. When it is the source of truth for 100x that number of people who don't care, the problem is "the system" is busted.

I've seen 2xxx used for ferry flights, twinned flights, canceled and "reincarnated" flight departing same day, etc.

This "same" two flight numbers arriving on the same day has happened to me several times. No issues to report.

I can see the problem here. If a flight is delayed until the next day, a new number will always be assigned because you can't have 2 flights departing on the same day with the same number.

However- because of the way that AC868 is normally a day flight, the delay of the one flight to a departure on the same day resulted in 2 flights arriving on the next day - at the same airport - with the same number (now - around 10 hours apart but still - same day). Thus, people looking on the arrivals side, would have had 2 flights with the same number arriving on the same day.

The problem will be that the scheduled arrival date was actually the day before - and you would have had to look at the previous day's arrivals, and see AC868 was delayed until T+1 in order to find the correct information. For the masses of this world - they would have never figured it out. As for the baggage belt identifier with the "A" assigned - that was probably just a baggage system flight number as flight numbers never operate or are published with letters assigned.

It's not so normal to assign a new flight number to a delayed flight when the departure is the same day - but - perhaps that could be something AC could look at - especially for AC868 - mainly because of the arrival time and the mess that can cause.

This was a bit of an anomaly but you're right - AC created some confusion on the arriving end by not changing the flight number and perhaps should have done so right away.

Actually, you can have 2 flights with the same flight number / call sign departing the same day. Look at AC33 / AC34 for instance. Same flight number, departs on the same day, but the 2 segments are never in the air at the same time. Or what US carriers do with their flights with one flight number, with different segments operated by different equipment. What you cannot have is 2 flights with the same flight number / call sign in the air at the same time.

Air Canada likely renumbered the flight (by adding a character to change it to AC868x), but it wasn't reflected on the information screens and in the App. However, if you were to look at Flightaware or another flight tracking tool, it'd show up with the revised flight number.

Happens all the time, never had an issue with this. Sometimes, it's renumbered AC2xxx (so if AC34 is delayed leaving SYD, another plane would have operated AC2034 if they did not want to delay the YVR - YYZ segment), sometimes with just a character appended to the flight number.

Some USA legacy carriers would assign numbers like 8868 or 9868 to the extra section.

Took a look at ACA868 for Aug 23 - it looks like there was no such flight on Aug 23... However, there are 2 flights for Aug 24.

The situation was that the taxi transfer company simply monitors flights on the public displays, and do not get involved in flight tracking tools. In my case, just by chance, it would have been extremely awkward if the transfer company was not there, as we had abnormal (for us) checked baggage. Based on the information displayed by Heathrow, the taxi company would have left long before we got through. It was only my daughter who persuaded them to stay. Priority baggage labels and an EU passport also helped. But AC were the ones who caused this problem, and their London staff should have known about it when they were contacted.

The same thing could happen again, and ruin "meet and greet" arrangements.

I usually, when possible, give a quick heads up to the transfer service or to my "assistant" to give heads up to the transfer company of any delayed flight that I would be arriving on.

In my case, the original transfer company were unable to send a larger vehicle (for our oversized baggage). The new company had my flight number AC868, but it did not appear on the arrival screen. They made an intelligent (?) guess I had made an error with the flight number, and we would be on AC858, arriving from the same place, about 1 hr earlier. Obviously, I was in the air and could not be contacted.

There probably would have been no problem if AC had assigned a new flight number.