transportprof

Every summer, it seems that United's TATL and TPAC flights suffer from a spike of maintenance delays and cancellations. Why could this be?

Some recurring factors that occur during the summer include:

1. Hotter weather (at least at the lower altitudes) which could be harder on aircraft.

2. Maintenance staff take more of their annual vacations during the summer, reducing staff levels to fix the last minute breakdowns and equipment failures.

3. ????

Any other bright ideas about why summer seems to be a bad time to fly TATL or TPAC on United, if you want to stay close to the schedule on your ticket?

WineCountryUA

Not sure there is any real data data to support this thesis.

WX / thunderstorms are a definitely increased factor of delays / cancellations / irrops in the summer.

But running with the thesis, believe in the summer aircraft utilization is up perhaps allowing less time for preventive / routine maintenance.

JBord

I've always wondered about #2. In college, I would work summers at a large company in a regional distribution center. The long-tenured union members would have accrued so much vacation that they just took the summers off, so the company hired a couple dozen college kids every summer to replace them.

Of course, an airline mechanic is a highly skilled union job, so they can't be easily replaced for a few months, which would lend some weight to your theory.

Just another interesting tidbit. In the company I worked for, the manufacturing plants would shut down for 2 weeks every summer, but the warehouses would keep running and supplying customers -- basically we got no new product in, but still had to ship out what we had. So it's possible that vacations across mechanics, the distribution chain, or in other areas might contribute to slower maintenance...perhaps even in UA's suppliers.

Maybe this doesn't impact UA at all, but it was a fascinating inside view of the impact unions have on a business for a college kid.

lincolnjkc

I've read the UA/IAM contract* for UA maintenance employees, but I've never worked UA maintenance so I could be mistaken but my understanding is that UA allocates a certain number of "vacation" shifts across the year at each maintenance location and those are then bid/awarded in seniority order -- I would presume that this is to ensure relatively level staffing throughout the year and prevents "everyone in maintenance is on vacation this week" from being a problem -- at the expense of some poor schmuck having to take vacation the 3rd week of February, though.



*- I find reading contracts (and NTSB reports) is a good way to learn more about the world while putting myself to sleep when I'm on the road...Yes, I'm weird.

PBAudit

I do not believe there is a significant "Summer effect" on increasing maintenance issues. Instead, the increase in maintenance cancellations can largely be explained as follows;

3. More international flights during the Summer. Assume the % of delays and cancellations is the same in the Winter/Summer. If there is a 15% increase in flights in the Summer, then there will be a natural 15% "spike" in delays and maintenance.

3.1. With more flights during the Summer, there is less spare planes to swap out for maintenance. There is less/no margin of error and planes that would be swapped out in the Winter (with spare capacity), are, in the Summer, simply cancelled for maintenance issues. This lack of "safety stock" will create a disproportionate impact. The following is a simplified example (does not take into consideration types of planes, where planes are located, etc.).

Assume that in the Winter there are 50 international flights and in the Summer there are 60 international flights. There are 62 planes available. On average, 10% of planes have maintenance issues. During the winter, 5 flights are subject to cancel. However there are 12 "spare planes" which 4 of the 5 flights can go with a plane swap (1 cancelled international flight in the Winter). In the Summer, a 10% maintenance rate means that 6 flights are subject to cancel. However, there are only 2 "spare planes", which means, at minimum 4 flights are cancelled.

Thus, assuming a "natural maintenance issue rate" stays the same in Winter/Summer, you would "naturally" go from 1 (or 0) Winter cancellation to a spike of 4 (or more) Summer cancellations.

TA

Actually an increase in mechanical issues could conceivably increase even more than this:

If aircraft are scheduled in winter in such a way that gives them just enough maintenance/downtime to stay in good working condition, increasing their utilization could cut into that critical amount of maintenance and significantly increase their failure rate much more than just the % increase in flights/utilization.

But yes, if it's about simply adding more flights with different aircraft then a simple scaling would make sense. But I notice that UA's large aircraft are generally not sitting around unused.

sbm12

The fleet is scheduled more aggressively during the summer. Tighter turns, more flights and more limited spares. That all contributes to stresses on the system.

And it is on both the single and twin-aisle aircraft.

DENviaLAX

You are correct in that the company regulates when and how much vacation time can be used at different points throughout the year. For most (union) airline positions, vacation is bid for in seniority order. There are X amount of slots of each week in the year available to be chosen, as to ensure that there is always an adequate amount of manpower available to cover the operation at all times. That said, because it's done by seniority, the OP's theory that more senior employees take their vacation time during the summer is also correct.

I don't know the ins and outs of maintenance positions, but what tends to happen with this setup is that, while there is still adequate manpower available throughout all points during the year, the more senior employees (who tend to be more qualified for more things) are gone more during the summer months, and therefore the operation is being covered by newer, less experienced employees. Whether that actually has a tangible effect on MX issues occurring in the summer, I wouldn't know. But I do think it's a solid theory, as I know it's a definite issue in other areas of the airline industry that can impact reliability.

cur

it doesn't occur more

you just notice it more

see https://en.wikipedia.org/wiki/Confirmation_bias

that and there are likely fewer spares and likely more utilization of aircraft due to high consumer demand

ua mx employees are teamsters

and yes you are right, vacation bids by seniority

i was iam and i will tell you that vacation balances in the cba are negotiated hard with the company but it is clear in the cba that operational requirements come first. each point/base has different vacation distribution but generally with hub points there is are fewer vacation lines to bid during christmas and Thanksgiving week, tons during shoulder and off peak (also available for unpaid leave or vacation buyback), and a decent amount during summer. employees on vacation or on disability or on sickness or injury or training are then covered by by vr +stir (vacation relief + sick,training,&injury relief) lines (a different schedule every 30 days) that are bid on during shift bids. issues of short staffing start arising when the employees who bid vr + stir get the s or i in stir...but if the airline is smart they'll have spare relief lines

a check and line mx rosters are typically sorted and forecast 3-5 months out
b and higher tend to be a 6-12 month plan

halls120

And crew shortage as well. A few years ago, I was riding with a UA pilot on the Aero train to the C terminal at IAD. We started chatting on the train, and continued talking as we walked in the tunnel. I asked him how the merger was going so far - this was in 2012 - and he said be ready for a lot of cancelled flights in the summer. I asked why, and he said that the company was scheduling flights under the assumption that they would get enough pilots to work overtime, and he said they were overestimating how many would choose to do it.

sbm12

This is less of an issue now than then, at least for the pilots, as integration between the two halves of the company is complete. It only affects a few fleet types but it does make a difference.

halls120

The pilot I talked to never said it was an integration issue. He said the company was overestimating the number of pilots who were willing to work overtime.

fly18725

While not directly an integration issue, an imbalance in the two work groups could create a surplus on one side and a shortage on the other that would need to be remedied with overtime. Post-integration, you can manage this imbalance and improve the efficiency of scheduling, e.g. eliminating dead heads.

halls120

So how is that working out for UA this summer?

artvandalay

Good question. And what reason do we have to believe this sorry performance won't be repeated next summer?

Oscar's image is tarnishing. Where is the United Airlines damage control?