superhub
Posts: 398
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Precise Timing In US Airline Schedules

Sun May 21, 2006 1:12 pm

One thing I have noticed about US airlines is that they use very precise times for their schedules. For example:

DL 632 departs SFO at 8:30am and arrives ATL at 3:59pm everyday except Wednesday. On Wednesday, the same flight arrives at 4:02pm.

Another example:
AA1541 departs DFW at 8:49am and arrives SEA at 10:54am everyday.

As you can see, these schedules are very precise...contrast these with other airlines such as CX or BA, which schedule their flights to the nearest 5 minutes.

CX 460 departs HKG at 8:35am and arrives in TPE at 10:15am

BA 307 departs CDG at 10:50m and arrives at LHR at 11:15am


I can see why trains can implement timetables which are very precise... because trains in general departs/arrives at the very precise time (especially in countries like France and Japan). Trains also have less factors to think about when making their timetables...they don't have to think about weather (winds etc)...they just have to think about where other trains are, what speed they are going..how long are they going to dwell at stations etc.

Airlines, however, are very unlikely to arrive at precisely the scheduled arrival time. Other factors play in such as wind, congestion etc which will make the flight arrive earlier/later than the scheduled arrival times.

My question is...why do US airlines have such precise schedules, or why do international airlines round up their times to the nearest five minutes?

So for this example:
DL 632 departs SFO at 8:30am and arrives ATL at 3:59pm everyday except Wednesday. On Wednesday, the same flight arrives at 4:02pm.

Why don't they just say that the flight arrives at 4pm everyday except Wednesday when it will arrive at 4:05pm?


Alternatively:
BA 307 departs CDG at 10:50m and arrives at LHR at 11:15am

Why doesn't BA say that the flight departs at 10:51am and arrive at 11:16am?
 
TransWorldSTL
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RE: Precise Timing In US Airline Schedules

Sun May 21, 2006 3:50 pm

I think a long time ago someone told me it was to improve their on time performance. If they give exact times that are a little later than needed, they can arrive/depart while saving their on-time performance record.. I'm probably wrong but I remember hearing that..
 
SESGDL
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RE: Precise Timing In US Airline Schedules

Sun May 21, 2006 3:59 pm

Quoting TransWorldSTL (Reply 1):
I think a long time ago someone told me it was to improve their on time performance. If they give exact times that are a little later than needed, they can arrive/depart while saving their on-time performance record.. I'm probably wrong but I remember hearing that..

That's pretty correct. One reason airlines do it is to increase flight times. For instance, if I fly from MSP-ORD, a flight which is about 50 minutes, instead of a flight being from 12:45pm-1:45pm, airlines schedule it for like 12:45pm-2:16pm, for allowance of more taxi time, etc. Another reason is airlines are now using limited turnaround times. DL, for example uses 45 minute turnarounds for all narrowbody flights domestically when they can. So if a flight arrives at 2:16pm, it will depart again at 3:01pm. I'm gonna stop, because it's too late and I'm explaining it wrong... Sorry...

Jeremy
 
superhub
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RE: Precise Timing In US Airline Schedules

Sun May 21, 2006 4:10 pm

Quoting SESGDL (Reply 2):
One reason airlines do it is to increase flight times. For instance, if I fly from MSP-ORD, a flight which is about 50 minutes, instead of a flight being from 12:45pm-1:45pm, airlines schedule it for like 12:45pm-2:16pm, for allowance of more taxi time, etc

Thanks for the explanations TransWorldSTL and SESGDL.

But making arrival time later than needed does not really mean the times have to be that precise... In your example, they can schedule the flight to arrive at 2:15pm and then do a forty five minute turnaround and the flight will be scheduled to depart at 3:00pm.
 
Leskova
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RE: Precise Timing In US Airline Schedules

Sun May 21, 2006 5:22 pm

Those "precise" timings are also a means to get a better listing in CRS displays, since - as usual - most people will prefer a faster connection; so if AA lists it's flight as taking 47 minutes and UA lists it's flight as taking 46 minutes on the same route, UA's flight will be listed first (admittedly, that depends on the CRS and on the type of schedule/availability display being used).

Other than that, I really don't see any sense in it; as you say, the likelihood of the flight ever really hitting the mark of arriving at 2:16pm or 8:32am or whatever is really rather low.

Regards,
Frank
Smile - it confuses people!
 
BDKLEZ
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RE: Precise Timing In US Airline Schedules

Sun May 21, 2006 7:01 pm

As far as I'm aware, it reflects the runway slot that has been booked with the airport for that particular arrival or departure. A runway slot is literally an airline's permission to use the runway at any particular airfield.
Trespassers will be shot; survivors will be shot again!
 
superhub
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RE: Precise Timing In US Airline Schedules

Sun May 21, 2006 7:42 pm

Quoting BDKLEZ (Reply 5):
As far as I'm aware, it reflects the runway slot that has been booked with the airport for that particular arrival or departure. A runway slot is literally an airline's permission to use the runway at any particular airfield.

Then why doesn't BA implement precise-timing in their schedules? Slots are very tight at LHR.
 
LoneStarMike
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RE: Precise Timing In US Airline Schedules

Sun May 21, 2006 7:48 pm

I've always wondered about this, too. Southwest Airlines rounds all their arrival and departure times to the nearest 5 minutes.

Seems like it would make things easier for folks who work in scheduling to deal with five mminute increments, but then again I don't know since that's not my job expertise.

LoneStarMike

 
BDKLEZ
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RE: Precise Timing In US Airline Schedules

Sun May 21, 2006 7:54 pm

Quoting Superhub (Reply 6):
Then why doesn't BA implement precise-timing in their schedules?

Again, as far as I'm aware, it's a US thing. But please feel fre to correct me if anyone knows any different.
Trespassers will be shot; survivors will be shot again!
 
Leskova
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RE: Precise Timing In US Airline Schedules

Sun May 21, 2006 8:03 pm

Quoting BDKLEZ (Reply 8):
Again, as far as I'm aware, it's a US thing. But please feel fre to correct me if anyone knows any different.

It's primarily used in the US, that's true... I know that CM also schedules their flights this way, and I think I've seen the occasional other schedule in South America that looked like this; but other than that, the 5-minute-rounding is pretty much standard all over the world.
Smile - it confuses people!
 
grimey
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RE: Precise Timing In US Airline Schedules

Sun May 21, 2006 8:28 pm

And the funny part is, the flights are usually delayed by a few minutes anyway  Big grin

Quoting BDKLEZ (Reply 5):
As far as I'm aware, it reflects the runway slot that has been booked with the airport for that particular arrival or departure. A runway slot is literally an airline's permission to use the runway at any particular airfield.

Yes that is one reason why it is used, it may not show up on a BA ticket/timetable but in LHR in their office they might have that flight listed to an exact minute. For example a BA flight LHR-JFK may be shown to take off a 15:00 but in a LHR office that flight would be known to take off at 15:02.

Grimey
 
AlexPorter
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RE: Precise Timing In US Airline Schedules

Mon May 22, 2006 2:49 am

I have been on flights that depart the gate and arrive at the gate at the exact scheduled times! However, that isn't very often, but they're actually usually quite close.
Last Flight: SCX701 MSP-PHX B738 8Jan2008
 
hawaiian717
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RE: Precise Timing In US Airline Schedules

Mon May 22, 2006 3:07 am

Quoting BDKLEZ (Reply 5):
As far as I'm aware, it reflects the runway slot that has been booked with the airport for that particular arrival or departure. A runway slot is literally an airline's permission to use the runway at any particular airfield.

Except that slot time scheduling is somewhat rare in the US. There are only a handful of slot-controlled airports in the US, and most allow a particular landing and takeoff cycle, but don't specify an exact time.
 
DesertAir
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RE: Precise Timing In US Airline Schedules

Mon May 22, 2006 3:14 am

I have noticed on a number of flights, the time for the flight that the flight attendants give differs from the time given by the pilot/co-pilot. It seems to me that there are the official scheduled times and the real time taking into consideration weather, airport slots....
 
jcavinato
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RE: Precise Timing In US Airline Schedules

Mon May 22, 2006 3:35 am

What I would love to see is a posting of times that luggage starts to come out of the shoot. To me that is the real arrival time of me and my things.

IAH on US from PIT for years would take anywhere from 45-50 minutes for luggage to start coming out. CO was much better. In this way I always thought CO had the better true passenger transit time.
 
supa7E7
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RE: Precise Timing In US Airline Schedules

Mon May 22, 2006 4:25 am

Precise schedules help an airline be more efficient.

Of course you can't estimate today's flight to 1 minute. But your ESTIMATE of the flight time (taking past flight data into account) can be very precise, since it's a mathematical construction. Delta knows exactly how much time ATL-MCO needs to achieve a 90% on-time rate. Add one minute, your on-time rate will increase. But they want to avoid wasting minutes too, (expensive), so it's a fine balance. Leaving 5-minute intervals is a convenience for customers but it makes the schedule less optimal.
"Who's to say spaceships aren't fine art?" - Phil Lesh
 
CentPIT
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RE: Precise Timing In US Airline Schedules

Mon May 22, 2006 9:30 am

Quoting Jcavinato (Reply 14):
IAH on US from PIT for years would take anywhere from 45-50 minutes for luggage to start coming out. CO was much better. In this way I always thought CO had the better true passenger transit time.

US is historically known to take the longest amount of time with luggage in PIT. When flying with Delta in and out of PIT, the luggage is often at the carousel before I arrive. This is weird!
Pittsburgh International: US Airways---160 daily departures! (52 destinations)
 
jcavinato
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RE: Precise Timing In US Airline Schedules

Mon May 22, 2006 12:36 pm

Yet there were times on US at PIT when I was inbound late from somewhere and ran and rushed through the underground shuttle and was the last one to board to SCE. Connection from hell. On those trips I always wondered if my luggage made it. It always did.
 
N200WN
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RE: Precise Timing In US Airline Schedules

Mon May 22, 2006 4:12 pm

Southwest uses rounded times to the nearest five minutes. You won't find any 10:59 departures or 12:16 arrivals in the schedule. I think it's much easier for the customers to remember rounded times as well.

Quoting DesertAir (Reply 13):
I have noticed on a number of flights, the time for the flight that the flight attendants give differs from the time given by the pilot/co-pilot. It seems to me that there are the official scheduled times and the real time taking into consideration weather, airport slots....

I've noticed this on Southwest. The F/A's will always give the gate to gate time - which is the same as the time listed in the schedule. The pilots always seem to give fly time...wheels up to touchdown.
 
johnclipper
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RE: Precise Timing In US Airline Schedules

Mon May 22, 2006 7:35 pm

US airlines will only do this on domestic flights. I've noticed that on international flights, the US airlines follow the "rounded" 5 minute rule too.
"Flown every aircraft since the Wright Flyer" (guys, if you take this literally, then you need to get a life...)
 
cgnnrw
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RE: Precise Timing In US Airline Schedules

Tue May 23, 2006 3:32 am

Quoting Superhub (Thread starter):
On Wednesday, the same flight arrives at 4:02pm.

In the US, Wednesday is called "over the hump day" because it's in the middle of the work week. To get "over" the hump takes an airplane a bit more time. Perfectly logical can't understand why you even asked.  Wink  mischievous 
A330 man.
 
vv701
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RE: Precise Timing In US Airline Schedules

Tue May 23, 2006 12:50 pm

Quoting Superhub (Reply 6):
Then why doesn't BA implement precise-timing in their schedules? Slots are very tight at LHR.



Quoting BDKLEZ (Reply 8):
Again, as far as I'm aware, it's a US thing.



Quoting JohnClipper (Reply 19):
US airlines will only do this on domestic flights. I've noticed that on international flights, the US airlines follow the "rounded" 5 minute rule too.

My observation is that AIRPORTS in the US have timetables to the minute and elsewhere to the 5 minutes. So I believe BA cannot implement precise timing because at LHR it is down to BAA not BA. So yes it is a US thing but I believe not a US airline thing. So when US airlines go international they adoipt the international method because, for example, they can get an 1100, 1105 or 1110 slot at LHR but not an 1104 or 1107 slot.
 
3201
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RE: Precise Timing In US Airline Schedules

Tue May 23, 2006 1:19 pm

Quoting Superhub (Thread starter):
Southwest Airlines rounds all their arrival and departure times to the nearest 5 minutes.



Quoting N200WN (Reply 18):
Southwest uses rounded times to the nearest five minutes.

Rumor has it that at least one of the majors will be making this switch later this year. Don't waste bandwidth by quoting and saying "Source?" because I won't say any more -- but I believe this will really happen.

Quoting JohnClipper (Reply 19):
US airlines will only do this on domestic flights. I've noticed that on international flights, the US airlines follow the "rounded" 5 minute rule too.

Only on the non-US side of the flights. For example:

UA900 departs SFO 1:58pm, arrives FRA 9:45am
UA930 departs SFO 1:02pm, arrives LHR 7:10am
UA954 departs SFO 7:12pm, arrives LHR 1:30pm

UA955 departs LHR 10:05am, arrives SFO 12:57pm
UA931 departs LHR 2:15pm, arrives SFO 5:17pm
UA901 departs FRA 1:45pm, arrives SFO 4:12pm
7 hours aint long-haul
 
JAFA
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RE: Precise Timing In US Airline Schedules

Tue May 23, 2006 1:48 pm

My hypothesis is that the non-rounded times allow for a smoother hub operation. Imagine 10 flights pushing back at exactly 7:00am. The another 10 at 7:05, and another 10 at 7:10a.

By staggering the departures you need less push back crews, and have less congestion on the ramp.

Someone already mentioned the main reason, and that is to get preferential listing in the computer systems. It has been shown that flights can make or loose money by adjusting the departure time forward or backward a few minutes. This is most common with multiple carriers on the same route.
 
FlyDeltaJets
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RE: Precise Timing In US Airline Schedules

Tue May 23, 2006 2:10 pm

At DL we refer to that as Operation CLockwork. It is a ploy to minimize taxi-time and boost on time performance by having an off hour departure time.
The only valid opinions are those based in facts
 
penguinflies
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RE: Precise Timing In US Airline Schedules

Tue May 23, 2006 2:15 pm

UA use to have two HNL-LAX flights on two DC-10s leaving at 9:15pm and 9:16pm. Those flights usually left from gates right next to each other (gate 7/8 or 9/10).


Also scheduling probably keeps in mind that crew times limits for bid schedules, on-time performance, staffing levels at outstations, and marketing play roles in how flight times are created.
 
ContnlEliteCMH
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RE: Precise Timing In US Airline Schedules

Tue May 23, 2006 2:26 pm

I think, after more than 250 flights in the past 20 months, the words

"precise"
"timing"
and
"airline schedule"

should never be used in the same sentence.

Whenever I'd leave the office, my mates would say, "Have a safe trip." My response was always the same: "Safe is a foregone conclusion. On time is a different matter entirely." If you have absolutely have to be somewhere at a point in time, DRIVE. Otherwise, pad your schedule heavily, because while airline schedules may be precise, their execution is anything but.
Christianity. Islam. Hinduism. Anthropogenic Global Warming. All are matters of faith!
 
FlyDeltaJets
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RE: Precise Timing In US Airline Schedules

Tue May 23, 2006 2:28 pm

Quoting ContnlEliteCMH (Reply 26):
Whenever I'd leave the office, my mates would say, "Have a safe trip." My response was always the same: "Safe is a foregone conclusion. On time is a different matter entirely." If you have absolutely have to be somewhere at a point in time, DRIVE. Otherwise, pad your schedule heavily, because while airline schedules may be precise, their execution is anything but.

That's not nice. At JFK we strive really hard to get our flights out on time. Any delays we do have are minimal 20 mins at most. Time which can be easily made up in the air.
The only valid opinions are those based in facts
 
ckfred
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RE: Precise Timing In US Airline Schedules

Tue May 23, 2006 2:35 pm

Have you ever noticed during the announcement before the safety briefing that the F/A will give the exact flying time. On my last flight, LAS-ORD, the F/A gave our flying time as 3 hours and 11 minutes According to a friend of mine who flies for AA, this is the exact flying time from the flight plan and is wheels up to touch down.

As it turned out, the flying time was 3 hours and 21 minutes, because of weather at ORD. The arrival patterns were being stretched very far over Lake Michigan.
 
ContnlEliteCMH
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RE: Precise Timing In US Airline Schedules

Wed May 24, 2006 12:06 pm

Quoting FlyDeltaJets (Reply 27):
That's not nice. At JFK we strive really hard to get our flights out on time. Any delays we do have are minimal 20 mins at most. Time which can be easily made up in the air.

It wasn't intended to be nice. Or to be mean. It's merely a fact based at least on the contract of carriage that you offer to your very own customers. It says, in no uncertain terms, that the airline is not required to get you to your destination at the promised time. There only responsibility is to get you there. (And about JFK: DOT stats show you ranked 18th out of 31 for March 2006, with a 77% on time rate. That means there are a BUNCH of flights that don't make up time in the air.)

But the evidence is far more empirical. http://www.transtats.bts.gov/OT_Delay/OT_DelayCause1.asp?pn=1 says that only 75% of flights are on time. Let's pretend that an airline has an on-time rate of 90%, meaning one out of every ten flights is not going to be on time. In my case, that would mean 25 delayed flights in 20 months. But the rate is much less -- 75% -- which means that 25 flights out of 100 are delayed. Now, we see that of the 250 flights I've taken, nearly 70 would be delayed. My delays ranged from a few minutes, to 24 hours.

JFK's performance is not any better. DOT stats show that arrivals into JFK ranked 18th out of 31 for March 2006, with a 77% on time rate. That means there are a BUNCH of flights that don't make up time in the air going to JFK. And I'll bet they're average regarding departure delays -- about 20%. In fact, the stats show that more flights arrive delayed than depart delayed -- which means that on the whole, flights aren't making up time in the air. On the whole, they're losing it.

The airlines pad THEIR schedules? Nope. Travelers pad THEIR schedules! And it seems to go in spurts. I've had several weeks where everything runs as planned. Then I've literally had strings of weeks where NOTHING ran on time -- not the outbound trip, and not the return trip.

So I repeat: If you absolutely MUST be somewhere at a specific point in time, you'd better fly at least a day early. Or DRIVE. The airline cannot guarantee that you'll get there even remotely close to on time, and the statistics show that you'd better not count on it. Mind you, I'm a happy flier. I'm just telling it like it is.
Christianity. Islam. Hinduism. Anthropogenic Global Warming. All are matters of faith!
 
b741
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RE: Precise Timing In US Airline Schedules

Wed May 24, 2006 12:16 pm

This is also a Canadian system too. AC and WS flights are not rounded to the nearest 00.
Being Bilingual, I Speak English And Aviation