Commercial Air Carrier Logistics

Just wondering a bit how commercial air carriers work.

I presume there’s computer programs that tell them "Fly three 737-800s and one 737-700 each day from Minneapolis to Phoenix and charge X per seat when bought on Y day.

I know sometimes they have to fly pilots and crew as passengers from one airport to another, but do they ever have to shuttle empty jets? Are there only certain airports where they can park a jet overnight?

Do flight crew get to pick where and when they fly, whether they want to fly out to Hawaii and then back in a week, or just a couple of runs to and from Cleveland and be back home the same night?

I was stuck in Denver for an hour while a malfunctioning ventilation valve was replaced. Do airlines stock spare parts and mechanics everywhere or just where there major operations are? If a Southwest jet breaks down at a Delta hub, will Delta sell them a spare widget or even provide a crew to install it?

They were talking about maybe substituting another jet. I assume they couldn’t make another 737 magically appear, so they’d be taking one from the next flight and then bumping things around until they can finally get the original one fixed ro get a spare jet flown in? Or would they eventually cancel a flight rather than flying a spare in?

Once there was apparently a discussion about which of two jets was going from Midway to Minneapolis. What was the deal, as wouldn’t the computer tell them which to fly?

Some sort of computerised schedule linked to their crew rostering program, yes.

Normally only if there is a breakdown. They might have to ferry a broken aircraft to a maintenance base and/or a replacement aircraft to the outport. The schedule would be planned to avoid regular ferry flights.

This is typically done with a bidding system with preference given to the more senior crew members (in terms of time served with the company.) Every one bids for the trips they want and the higher your seniority the more likely you will get your preference.

It all depends on the airline. They won’t have their own maintenance everywhere but they may have contractors they can use and yes they may use a competitor’s parts. It comes down to risk management. Having spares and engineers everywhere is expensive but so is having a minor breakdown that leaves the aircraft grounded because there is no one to fix it. Another factor is that many defects can be signed off without being fixed if there is enough redundancy in the system. Sometimes the flight crew themselves can do this but often they can’t. At the very least each port should have an engineer who can sign for derring defects.

It all depends. They will do what they can with minimal disruption and minimal cost.

Things change. Maybe the one scheduled to do the flight had maintenance due and doing its scheduled flight had it running close to running out of hours. In our company aircraft swaps happen for various reasons.

some of the math involved in scheduling uses this

Linear programming - Wikipedia

which is actually a pretty new branch of math, only been around since WW II

Years ago (it made the news) a 747 flew from Japan to London with a single passenger.

The plane had a serious mechanical problem which grounded it for a bit over 2 hours. All other passengers booked on other flights. One woman was in no hurry, so waited for the plane.
The plane had to be in London for scheduling reasons, so it flew.

This was over 20 years ago - I’m guessing the scheduling programs have figured out a better way to fill in for that plane than to move it empty halfway around the world. Or maybe the story was a bit more complex than a news reporter reported. It’s happened.

An extra complication is the need to reserve take-off and landing slots. Back in 07 there was a story about BA flying empty planes across the Atlantic: http://www.dailymail.co.uk/news/article-493357/Green-BA-flying-ghost-planes-Atlantic.html

They also have to contend with rules about duty hours: BA passengers left for a night on the tiles as plane flies home empty. http://www.independent.co.uk/travel/news-and-advice/ba-passengers-left-for-a-night-on-the-tiles-as-plane-flies-home-empty-8640806.html

I have a youngster who flies for the airlines.

He says the bidding software is in some ways like an online dating site. As Richard Pearse mentioned above, the individual pilot’s seniority number “weights” his choices over other pilots, but the program allows them to prioritize their personal preferences. He can assign weights to values such as: Multiple days at home, Must-be-off days (like for a wedding or something), certain airports, day/night duty, weekends off (as opposed to weekdays), concentrating duty time at beginning or end or month, etc. It’s amazingly complicated, and he learned quickly to maximize his “turns” such that his duty day ends away from station (not at home airport). This maxes out his daily per-diem, which is a moneymaker for a young single guy who can exist on ramen/etc. instead of expensive hotel meals.

[Boring sidenote] I joined him and his crew for a round-trip flight last week (just to say I’d ridden in the back of my kid’s airplane) and was surprised at how frugal the young crew was when we ate at the hotel that evening. Once I assured them I’d pick up the tab for the entire group, they exhibited a bit more enthusiasm with their menus. :stuck_out_tongue:

Apparently it’s not all that uncommon.