Pricey Tripped Up,

Final September, my husband and I left our youngsters with their grandparents and set off to Eire. Our $2,132 itinerary took us from Minneapolis to Toronto to Dublin on tickets booked on United Airways by way of Expedia however finally operated by Air Canada, a United companion. We had boarded our connecting flight in Toronto (and I used to be already dozing in my seat) when the captain introduced an operator had crashed the jet bridge into the starboard engine. We got lodge vouchers and advised we might be rebooked for the following day. Checkout time got here and went and not using a phrase, so we went to the airport and have been advised to name Air Canada customer support. An agent booked us a flight for that night, and we printed out boarding passes at an airport kiosk. However once we tried to board, we have been advised the boarding passes have been invalid. Ultimately, we have been supplied two choices for the following day: Fly to Dublin through Newark, or return to Minneapolis. We lower our losses and went dwelling after staying the evening in Toronto at a lodge. However United refunded us solely $1,087, barely half of what we paid. Air Canada did reimburse us for the second lodge and different bills, however we consider the airways owe us not solely a full refund, but in addition 400 Canadian every ($295 apiece) below Canadian legislation for denied boarding. Each refused. Are you able to assist? Michelle, Edina, Minn.

Pricey Michelle,

I discovered the 58-page file you despatched alongside along with your story to be fairly convincing. (It additionally satisfied me that both you or your husband is a lawyer, which seems to be true.)

I disregarded Expedia, since your journey had already began, and reached out to United and Air Canada — as you flew on an airline’s companion, it’s a code share association. A spokeswoman for United, Erin Jankowski, rapidly despatched me an announcement noting that the refund you obtained from United was as per Air Canada’s directions and referred all different inquiries to it.

Air Canada, then again, took nearly two weeks to get again to me, and its response was underwhelming.

“Our information point out these prospects weren’t denied boarding in Toronto,” wrote Peter Fitzpatrick, a spokesman for the airline. “As an alternative, it seems that following the cancellation of their authentic flight to Eire they opted to return to Minneapolis from Toronto reasonably than go to Dublin following the delay. As soon as that was recognized, we did rebook the purchasers on a flight again to Minneapolis.”

No compensation, no phrase on the $1,045 nonetheless lacking out of your refund and no clarification as to the way you have been turned away on the gate on your second flight and but “not denied boarding.”

Air Canada did give you and your husband a credit score value 1,200 Canadian {dollars} towards a future flight, Mr. Fitzpatrick wrote to me, “to account for the impression on their journey plans and expertise.”

There was no response to my direct query asking why your boarding passes didn’t work the second evening. In reality, it isn’t even clear from Mr. Fitzpatrick’s preliminary assertion that Air Canada believed you even tried to board, regardless of the boarding passes you included within the file despatched to me and the 2 airways.

I wrote again with extra pointed questions, due to what I discovered after studying up on the Canadian Transportation Company’s air passenger protection regulations and talking with Tom Oommen, the director common of the C.T.A.’s Evaluation and Outreach Department.

“We now have what I might name a really full holistic system of shopper safety for airways,” he mentioned. For instance, when flight disruptions happen for causes inside an airline’s management and the airline can not get passengers onto one other of its personal flights inside 9 hours, it should e book the passenger on any airline, together with opponents it doesn’t have agreements with, a requirement that the USA doesn’t impose.

Mr. Oommen additionally famous that if a passenger is caught halfway by way of a visit and isn’t pleased with the choices to proceed on, the airline should provide to rebook that passenger “on a flight again to their level of origin freed from cost and refund their complete ticket.”

He wouldn’t particularly remark in your case, however that’s precisely what occurred to you. (The one exception to those guidelines is when the disruption isn’t inside the airline’s management, Mr. Oommen mentioned, however when a mechanical drawback is attributable to an airline worker or contractor, “it’s arduous to make that argument.”)

There are additionally many circumstances during which Canada requires airways to compensate passengers — between 400 and a pair of,400 {dollars} — for flight delays, cancellations and denied boarding inside the airline’s management. There may be an exception for when such points have security implications, which might apply to the primary evening’s engine harm, however not, it appears to me, for the second evening’s nonfunctioning boarding passes. That sounds so much like denied boarding.

This time, you heard again earlier than I did, and forwarded me a number of emails from Air Canada, together with one which mentioned the service had authorised a money cost of 400 {dollars} per traveler. Then Mr. Fitzpatrick emailed me to say you’ll obtain a full refund.

So you bought what you requested for, however after all you’ll reasonably have gone to Eire. And what occurred, precisely, when Air Canada refused to board you in Toronto? Mr. Fitzpatrick advised me United had canceled your ticket earlier than you even obtained to the gate.

I discovered that complicated — the boarding go bears an Air Canada ticket quantity, and also you had not even spoken to United that day. So I obtained again in contact with United’s Ms. Jankowski, who regarded into the scenario additional and located that “United canceled the tickets after sending messages to the working service, Air Canada, informing them that the tickets had not been correctly reissued to the rescheduled flight.”

Apparently, someplace within the interfacing bowels of the 2 carriers’ programs, your Air Canada boarding go was invalidated by United, and neither airline contacted you. And that’s too dangerous, as a result of Mr. Fitzpatrick later confirmed that second flight left with empty seats.

If you determined to simply go dwelling, the Air Canada consultant on the airport mentioned you needed to name United. The method to untangle the mess and get you booked on a flight again to Minneapolis required hours and 6 totally different United customer support representatives and supervisors.

Your expertise is an efficient purpose for all of us to keep away from code shares until they’re crucial — similar to when an itinerary contains flights operated by totally different airways.

All this since you initially booked Air Canada flights as United code shares — a selection you discovered on Expedia. Once I just lately ran a Minneapolis-to-Dublin search on Expedia for per week in April, the primary two selections that appeared have been the identical route through Toronto with no worth distinction, one booked immediately on Air Canada and the opposite as a code share on United. Assuming you noticed the identical factor final yr, I guess that in the event you had booked the Air Canada selection, you’ll have made it to Eire, albeit a day late. All of the extra purpose to e book immediately, with one airline.

There may be one remaining thriller: Why wouldn’t Air Canada admit this was a case of denied boarding, and comply with the required C.T.A. rules? Sure, your case doesn’t exactly match the agency’s official definition, which is written to explain overbooking or adjustments in plane, but when an airline erroneously cancels a passenger’s ticket after it has already printed a boarding go, and you might be stopped on the gate, what’s that?

I offered this as a theoretical scenario to the Mr. Oommen of the C.T.A.

“Traditional denied boarding is what you’re describing,” he mentioned.

Meaning you can file for a further 400 {dollars} every for this second incident, and put that towards a brand new flight to Eire — say, on Aer Lingus, direct or by way of Chicago.

Should you want recommendation a few best-laid journey plan that went awry, ship an e-mail to TrippedUp@nytimes.com.