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I just realized shortest JFK - DEN flights are ~4h40m (280 min) and shortest JFK - LAX flights are ~6h (360 min). I'm talking about currently available commercial flights.

NY - DEN (straight line) distance is ~1625 mi, NY - LA distance is ~2450 mi (approximate measures using Google Maps' Measure Distance). So NY - DEN is about 0.663 of NY - LA distance-wise, while JFK- DEN flight takes about 0.777 of JFK - LAX flight time-wise.

In other words, going by distance, I would have expected JFK - DEN flight to be about 42 minutes shorter, or slightly under 4h. Any idea where the ~15% increase in flight time from what I expected comes from?

DeltaLima
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steady rain
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    Different aircraft, different routes, spacing, arrival slots, it can be a number of factors, distance isn't the only thing that determines how long a flight takes. – Ron Beyer Mar 13 '17 at 17:17
  • Thanks @RonBeyer - yes, I understand that, I just found the difference quite big. To put it another way - I expected that the differences would be happening on both routes, so given the variety you would have shorter ones on JFK - DEN. Or am I just imagining and this is common occurrence? – steady rain Mar 13 '17 at 17:20
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    Also, commercial flights include estimated taxi time, so the flight time will scale differently than the taxi time which depends on the specific airports involved (i.e. taxi time at DEN will very likely be much less than taxi time at LAX). Therefore, your ratio would make more sense (assuming the same cruising speed which isn't necessarily the case either) if it only looked at flight time instead of block (trip) time. – Lnafziger Mar 13 '17 at 17:27
  • Thanks @Lnafziger - OK, I was not aware of that, thanks for clarifying. However, that only tips what I find unusual in the wrong direction, no? I.e. given this, the actual JFK - DEN / JFK - LAC time ratio (0.777 I calculated above) is even bigger if calculated using flight times instead of trip times. – steady rain Mar 13 '17 at 17:39
  • Punching the NFDC preferred routes into SkyVector, I get ETE for JFK to DEN of 3:39 and and ETE for JFK to LAX of 5:14. Based on your original numbers, that's an hour for combined taxi times on the DEN run and about 45 min combined on the LAX route. The DEN route time seems to be padded by at 15 - 20 minutes. Twenty minutes at each end is not atypical for taxi time allowance. – Gerry Mar 13 '17 at 18:58
  • @Gerry That difference could be due to time of day as well (taxi time will vary depending on what time of day the flight takes place). – Lnafziger Mar 13 '17 at 19:00
  • @Lnafziger True. It could also just be the airline looking at its historical flight data and recognizing some systemic delays for that route. With the FAA scoring them for on-time performance, it doesn't pay to be over-optimistic. – Gerry Mar 13 '17 at 19:05

2 Answers2

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There is certainly a difference, but most of it definitely has a good explanation. Most of it is overhead such as taxi time that applies to both flights (almost) equally. This has a relative big impact on short flights.

The taxi out time for both flights will be about 27 minutes; JFK is not exactly known for its quiet taxiways. Both flights will add about 30 nautical mile for their departure route.

Both flights will fly approximately great circle routes, probably less than 2% extra distance during cruise.

The LAX flight will typically do a straight in arrival, almost no extra distance there.

The DEN flight will typically do a full arrival, 30 NM extra distance there.

The taxi in at LAX is 13 minutes on average, and 9 minutes at DEN.

Let's assume that both aircraft fly 460 knot true airspeed with 20 knots headwind during cruise, so 440 knots ground speed.

My estimates for the total flight times are then:

JFK-LAX

  • GC distance 2150 n.m
  • Departure detour 30 n.m
  • Arrival detour 0 n.m (straight in)
  • Cruise detour 25 n.m

  • Total distance 2205 n.m

  • Taxi out: 27 minutes

  • Climb out: 60 n.m. @ 300 kts = 12 minutes
  • Cruise: 2085 n.m. @440 kts = 4 hour 44 minutes
  • Descent/Landing: 60 n.m @ 240 kts = 15 minutes
  • Taxi in: 12 minutes
  • Total time: 5h50 minutes
  • Margin: 10 minutes

JFK-DEN

  • GC distance 1400 n.m.
  • Departure detour 30 n.m.
  • Arrival detour 30 n.m.
  • Cruise detour 15 n.m.

  • Total distance 1475 n.m.

  • Taxi out: 27 minutes

  • Climb out: 60 n.m. @ 300 kts = 12 minutes
  • Cruise: 1355 n.m. @440 kts = 3 hour 05 minutes
  • Descent/Landing: 60 n.m @ 240 kts = 15 minutes
  • Taxi in: 9 minutes
  • Total time: 4h07 minutes
  • Margin: 33 minutes
DeltaLima
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    Great analysis, thanks DeltaLima - so basically it's a combination of non-cruise overhead on short flights and bigger DEN margins? In hindsight this makes sense: 0nm flight would still be cited as a 40m-1h flight due to overhead + margin. – steady rain Mar 27 '17 at 16:35
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I did an analysis of flights in the last 6 weeks of flights to those destinations. Different airlines fly different aircraft to them. The only two aircraft I could find that flew to both was A320 and A321. Averaging out flight times and dividing it by the distances you listed I only found a 4% difference between the two. That could be accounted for by the extra time in cruise between the two. Here is a table with my numbers.

enter image description here

  • Note that the data included only one B739 flight.
TomMcW
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