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 via 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 resort vouchers and instructed we’d be rebooked for the subsequent day. Checkout time got here and went with out a phrase, so we went to the airport and have been instructed 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 after we tried to board, we have been instructed the boarding passes have been invalid. Finally, we have been provided two choices for the subsequent day: Fly to Dublin by way of Newark, or return to Minneapolis. We minimize our losses and went dwelling after staying the evening in Toronto at a resort. However United refunded us solely $1,087, barely half of what we paid. Air Canada did reimburse us for the second resort and different bills, however we imagine the airways owe us not solely a full refund, but in addition 400 Canadian every ($295 apiece) beneath Canadian regulation for denied boarding. Each refused. Are you able to assist? Michelle, Edina, Minn.

Pricey Michelle,

I discovered the 58-page file you despatched alongside together 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 omitted 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, shortly despatched me a press release 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 virtually two weeks to get again to me, and its response was underwhelming.

“Our data 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 fairly 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 price 1,200 Canadian {dollars} towards a future flight, Mr. Fitzpatrick wrote to me, “to account for the influence 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 realized after studying up on the Canadian Transportation Company’s air passenger protection regulations and talking with Tom Oommen, the director basic of the C.T.A.’s Evaluation and Outreach Department.

“We’ve got what I might name a really full holistic system of client 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 rivals it doesn’t have agreements with, a requirement that america doesn’t impose.

Mr. Oommen additionally famous that if a passenger is caught halfway via a visit and isn’t proud of 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 total 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 will not be throughout the airline’s management, Mr. Oommen mentioned, however when a mechanical downside is brought on by an airline worker or contractor, “it’s exhausting to make that argument.”)

There are additionally many circumstances wherein Canada requires airways to compensate passengers — between 400 and a couple of,400 {dollars} — for flight delays, cancellations and denied boarding throughout 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 injury, however not, it appears to me, for the second evening’s nonfunctioning boarding passes. That sounds loads 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 in fact you’ll fairly have gone to Eire. And what occurred, precisely, when Air Canada refused to board you in Toronto? Mr. Fitzpatrick instructed me United had canceled your ticket earlier than you even received to the gate.

I discovered that complicated — the boarding cross bears an Air Canada ticket quantity, and also you had not even spoken to United that day. So I received 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’ techniques, your Air Canada boarding cross was invalidated by United, and neither airline contacted you. And that’s too unhealthy, 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 cause for all of us to keep away from code shares until they’re mandatory — similar to when an itinerary consists of 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 not too long ago ran a Minneapolis-to-Dublin search on Expedia for every week in April, the primary two selections that appeared have been the identical route by way of 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 12 months, I wager that for those who had booked the Air Canada selection, you’ll have made it to Eire, albeit a day late. All of the extra cause to e-book immediately, with one airline.

There may be one closing thriller: Why wouldn’t Air Canada admit this was a case of denied boarding, and observe 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 cross, and you’re stopped on the gate, what’s that?

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

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

Which means you would file for an extra 400 {dollars} every for this second incident, and put that towards a brand new flight to Eire — say, on Aer Lingus, direct or via Chicago.

For those who want recommendation a few best-laid journey plan that went awry, ship an electronic mail to TrippedUp@nytimes.com.