Transpacificflyer

Your intent may be pure and wholesome, but as explained up thread, it is a term easily taken out of context because in business operations it is often associated with misrepresentation at best and fraud and deception at worst. An airline is a business, so the business context of padding would be used. For example;
1. The Padding That Hurts: Auditors cannot ignore expense account cheating by management. Journal of Accountancy, Nov. 2003
2. Prevent Expense Account Padding with the Right Policies
3, Resume padding happens at all levels of employment, as indicated by the HireRight survey. While more often associated with front-line employees, former Yahoo CEO Scott Thompson was forced to resign his position on May 13, 2012, after shareholders and company leaders became aware that his degree was inaccurate .

canadiancow

That's like saying "knife" is a bad word because people have been stabbed to death.

ou81two

Well, when one of your main hubs is San Francisco and it has 0 snowstorms then you get a better on time percentage. Same for ATL, IAH, etc. Most spoiled is Hawaiian Airlines with its Honolulu hub flying mostly to west coast cities. There's a few reasons.

gcashin

I would expect SFO to be a drag on any domestic carrier's OTP due to the frequent ATC restrictions. A routine "low-ceiling" day in SFO can cancel/delay more flights (short-haul domestic tend to take the brunt of the issues) than snow at one of AC's hubs.

So while UA may be a bit more conservative with their longer block times on YYC-IAH, I don't take exception to it, as I much prefer to arrive as scheduled or a few mins early than arrive late due to the typical things that chew up those extra few minutes (e.g. stronger headwinds, waiting for takeoff position).

LarryJ

Different airplanes are designed to be the most efficient at different speeds. Airplanes designed for long-haul flying are designed to fly faster. For a given airplane, the most efficient speed for a particular flight will vary with weight, temperature, altitude, and winds. i.e. it is more efficient to fly faster into a headwind and slower with a tailwind. Most airlines will increase speed when they are projecting a late arrival and use the most economical speed when doing so will still arrive on time.

In this case, IAH-YYC, IAH is United's hub so the UAL flight is departing during a departure push which ramp congestion, taxiway congestion, and a line of departures to follow. The AC flight may be departing between UAL pushes so no ramp congestion, no taxiway congestion, and no line at the departure runway. That would account for most, of not all, of the 25 minutes.

Terence.Hill

The planes probably don't fly much faster but the entire team performs faster or is at least more confident about it.

irishguy28

Absolutely. "Padding" allows many more flights to arrive early or on time for which an "unpadded" flight would arrive late.

(If students that "cheat" on their tests more frequently get good marks, is it really cheating?)

CZAMFlyer

This was recently discussed in an OTP thread. Adding to gcashin's good point about SFO, UA also has hubs in wintry Denver, Chicago and Newark, all of which are busy airports surrounded by congested airspace. Similarly, Westjet has the same hub airports as AC, and Delta hubs in Minneapolis and Salt Lake. All airlines rank higher than AC in OTP.
I'm not sure how ATL factors into the conversation.

Fiordland

That is easy to explain. UA is probably selling a similar number of seats between YYC and IAH. What United is probably selling a lot more of are flights between YYC and Florida, the rest of the southern US and South America that happen to involve a change of aircraft in IAH.

On the AC side, YYC is a not a great airport for connecting traffic to/from the US.

As for how fast the UA or AC aircraft travel, both airlines likely operate their flights at the speed that burns the least amount of fuel unless it would cause a late arrival, then they may rev up the engines a bit more.