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Jawaiiansky66
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Joined: Fri Dec 09, 2016 12:03 am

Making up for delayed time...how do airlines recover to get aircraft back on time?

Tue Feb 21, 2017 3:12 pm

Howdy all. New to AIRLINERS.NET and my first topic post so please be kind! Love aviation but unfamiliar with the logistics of the airline industry. :bouncy:

Flew from YVR to HNL on AC ROUGE on February 3rd to see my sick dad and got caught in the beginnings of that snow storm that blanketed much of the Pacific Northwest with over a foot of snow. The flight was initially on time but the snow and de-icing eventually delayed the flight 2 hours. When we arrived in HNL, you could see the tired and worn out (and unhappy) vacationers waiting to board the flight back to YVR. The looks on their faces reminded me of the last AC ROUGE flight I took to HNL two years ago where the flight was around 6 hours late. I love HNL airport but realized how limited the place is after 11pm. It was torture as the airport does not have any decent places to sleep for a few hours. This got me thinking about aircraft scheduling in general.

So, my question...what are some creative procedures airlines use to reset aircraft schedules to recover from the pile-up of delays? Like a bus, if a flight runs a few minutes late and continues to have delays through its daily schedule, this could eventually add up to hours of delays. Is there a down time for each aircraft that allows the airline to reset their schedule for the aircraft or does scheduling just sub in another available aircraft to make it all work? This leads me to another question, how many aircraft would an airline need for a daily flight from, lets say, YVR - HNL?

Thanks in advance for any answers...
 
FGITD
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Joined: Wed Jun 15, 2016 1:44 pm

Re: Making up for delayed time...how do airlines recover to get aircraft back on time?

Tue Feb 21, 2017 3:57 pm

One simple solution is aircraft swaps, wherever possible. Typically only works at hubs though.

Another way which from my experience is more common on long haul, is a long turn time. Not all stations/flights are a minimum turn, meaning the aircraft could arrive late, but still have plenty of time before it's next scheduled departure.

For large scale events like snow, I don't know a whole lot, but I've seen entire schedules cancelled, with the intention of just starting from scratch the next day.

Perhaps someone with more dispatch or aircraft rotation knowledge can answer a little bit better though
 
ZanVetter
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Re: Making up for delayed time...how do airlines recover to get aircraft back on time?

Tue Feb 21, 2017 3:59 pm

A hypothetical airline that operated that single city pair (YVR-HNL) once a day and did nothing else would need one aircraft. The aircraft would be flying approximately 12 hrs per day with (say) 1 hour or perhaps 90 minutes in the turnaround at HNL, leaving more than 10 hrs for servicing, maintenance back at home base, as well as time for catching up for delays. However, aircraft periodically need maintenance more in-depth than what can be covered in between daily flights. The most in-depth maintenance checks can have an aircraft down for as long as a month, but may only need to be accomplished every 5 years. Knowing this, operating that single city pair and nothing else would really require 2 aircraft. But now you're out of business, because 90% of the time the second aircraft is just sitting on the ground instead of generating revenue. So the executive team comes up with a second city pair to serve, in order to put the second aircraft to work. But, you still need a spare. So 3 aircraft. Two working and one full spare? You're still out of business in a very short period. As you can see, the short answer is that there is no magic formula; airlines try to operate their network with the fewest airplanes possible, without having to regularly cancel or delay flights. Most large network carriers can recover delays and be back on a normal schedule within one day, because of the flexibility available with having several hundred aircraft and thousands of pilots and flight attendants. A small company gets stretched to the max very easily, which puts pressure on the pilots, engineers, and other staff to "get 'er done", often times at the expense of safety.
 
Cipango
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Re: Making up for delayed time...how do airlines recover to get aircraft back on time?

Tue Feb 21, 2017 4:36 pm

Scheduled have "firebreaks" built in. This is essentially a longer buffer time in aircraft rotations to absorb any delays.

Also at hub airports, a larger airline may swap multiple aircraft schedules around (sometimes up to a dozen) to make sure there is no further delay. This can be aircraft types or tail changes.
Let's fly! Unless it's on a CRJ 200, then I'll stay down here.
 
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PHBVF
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Re: Making up for delayed time...how do airlines recover to get aircraft back on time?

Tue Feb 21, 2017 4:54 pm

There are several ways to recover a delay.
One of which is padding in the rotation. I believe DL does this a lot. Plan excessive turn around times, which mostly won't be needed and can help the reach a high punctuality percentage.
- Another as mentioned before is shifting schedules. Systems of this (that I am familiar with) are basically a drag and drop system in which flights can be moved between aircraft.
- What also happens sometimes at larger airlines is that aircraft are given a day off for minor repairs/checks and washing, while also being on standby for a possible schedule change.
- Some airlines have a procedure to speed up the turnaround, if it wasn't too short to begin with.
- In dispatch a higher cost index might be selected, though this ussualy only benefits longer flights.
- In flight crew can request shortcuts and monitor the winds aloft to see if a different level might result in better ground speeds.

So there are plenty of option, some making up more time than the others.
Licensed 777/787 driver
 
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Jawaiiansky66
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Re: Making up for delayed time...how do airlines recover to get aircraft back on time?

Wed Feb 22, 2017 2:55 pm

Thanks guys for the great replies...
 
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hongkongflyer
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Re: Making up for delayed time...how do airlines recover to get aircraft back on time?

Wed Feb 22, 2017 3:41 pm

in addition, airlines can wet-lease a plane to operate flights on behalf of them if the chain delay can't be solved shortly
 
KEWR2014
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Re: Making up for delayed time...how do airlines recover to get aircraft back on time?

Wed Feb 22, 2017 3:54 pm

I work in an enroute facility and everyday I get numerous requests from aircraft asking for shortcuts cause "we are running very behind". Usually we try to accomodate them if military airspace, flow, or sequencing allows!
 
Flighty
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Re: Making up for delayed time...how do airlines recover to get aircraft back on time?

Wed Feb 22, 2017 4:07 pm

Not a real expert on this, but as said before, schedule padding, aircraft swaps and spares. Finally, the overnight clock reset.

So if you have 8 flights going from A to B, and they are all 1 hour late, you can trade 7 of them backward. This fixes the last 7 of them. The first one needs a plane, so you activate your spare and fly that one. At the end of the evening your 8th plane slides in super late and replaces the spare, so you are golden. A bad problem was solved with only a few hours of 1 spare.

Or, even worse, after you tried everything 8 flights are still late. The next morning, they can depart on-time and it is fixed. It is fairly common that flights departing in the evening suffer from cascading delays. While the 6am departure the next morning is on-time because the night absorbed the delays. And obviously the legal rest is in there too. They schedule crews very cleverly to make sure of that. Last-in is the last-out, so they can sleep till 10am if they arrived at 2:00am.

In true operational meltdowns, like JetBlue in 2007 (exactly 10 years ago), all the pilots are timed out, so the morning start can't occur. Then they need a custom game plan to get their flights running again. Basically it is all about where you start in the morning. If the plane + crew is in the wrong city at 6am, the day will go poorly.
 
32andBelow
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Re: Making up for delayed time...how do airlines recover to get aircraft back on time?

Wed Feb 22, 2017 5:27 pm

There's many techniques. One I didn't see covered is a strategic cancellation. If you have a route that is lightly booked and there are other options for those passengers you can cancel a turn. Then the following turn and everything behind it can get back on time. Obviously this would effect the routing of that aircraft and if it is coming back to the hub or continuing somewhere else b
 
alasizon
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Joined: Sat Apr 28, 2007 8:57 pm

Re: Making up for delayed time...how do airlines recover to get aircraft back on time?

Wed Feb 22, 2017 9:26 pm

The other thing to consider is what the minimum turn time is for a given flight. As an example, our minimum turn time for a 50 seat RJ in a hub is 35 minutes. When I was an agent, I routinely was able to turn these flights with another agent in less than 25 minutes (fastest ever done for me was a 16 minute turn). That puts 10 minutes back on the clock that otherwise would have been lost if we simply just went for the 35 and settled there.

Another thing that is routinely done is a swap that will create a negative turn (inbound is scheduled to arrive with less than the minimum turn time prior to the departure) for one flight in order to get another out sooner. This is typically done when the flight with a negative turn has a longer ground time at the downline station than another flight.

Example:
Aircraft 1
Flight A Outstation - HUB SKA 0900
Flight B HUB - Outstation SKD 1000, SKA 1120
Flight C Outstation - HUB SKD 1215, SKA 1345
Flight D HUB - Outstation SKD 1430

Aircraft 2
Flight E Outstation - HUB SKA 0830
Flight F HUB - Outstation SKD 1000, SKA 1135
Flight G Outstation - HUB SKD 1205, SKA 1345
Flight H HUB - Outstation SKD 1430

Minimum Turn time is 25 minutes in the outstation and 30 minutes in the hub.

In this example, lets say Aircraft 2 is delayed 1:30 for flight E, this would make the new ETA 1000, this would cause a 30 minute delay on flight F, a 25 minute delay on flight G and a further delay of 10 minutes on flight H. If the B/C and F/G routings are swapped, F&G both operate on time. B would end up departing 30 minutes late but flight C would still depart back to the hub on time. As such, instead of taking 3 delays due to a late arriving aircraft, only one delay is taken and is recovered quickly.

The new routings would look like this:
Aircraft 1
Flight A Outstation - HUB SKA 0900
Flight F HUB - Outstation SKD 1000, SKA 1135
Flight G Outstation - HUB SKD 1205, SKA 1345
Flight D HUB - Outstation SKD 1430

Aircraft 2
Flight E Outstation - HUB ETA 1000
Flight B HUB - Outstation ETD 1030, ETA 1250
Flight C Outstation - HUB SKD 1215, SKA 1345
Flight H HUB - Outstation SKD 1430

Far better to take only one delay rather than three (not counting the originally delayed Flight E).
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