Anyone have an idea why this morning's flight 510 from DEN-LGA was diverted to CAK for weather (where as of now it still sits) whereas the United flight that left DEN a few minutes later landed at LGA just fine?

Would this have been a pilot or airline or airport decision? Had all flights been diverted, that would have been more clear but I find this one confusing. Does Frontier just not have enough clout at LGA to get priority in the queue?

Finally, should Frontier cough up anything (aside from packets of goldfish crackers) like a voucher in response or since it was weather-related is that out?

Thanks!

LGA wasn't that bad as far as weather at that time... it was a large line of thunderstorms and an Air Traffic Control "airspace flow program" through that front. LGA wasn't the only airport affected.

F9510 http://flightaware.com/live/flight/F...645Z/KDEN/KCAK Yellow and Red are thunderstorms.

UAL310 http://flightaware.com/live/flight/U...650Z/KDEN/KLGA

1) Just a wild guess that the difference in metal A320 vs B757 or the way they were dispatched gave United enough range to fly totally around the front. It looks like they both started with a similar route but Frontier for some reason midway tried a more direct route. Maybe actual fuel burn was more than planned and of course the possibility of a diversion to Canada isn't really an option. Pilots and their dispatchers coordinating with ATC would make a route change and diversion decision in such a case.

2) LGA could certainly have been packed with aircraft waiting for departure clearance with the AFP in place. So even if you could get in would you get a gate? (how many does F9 have there) Here's an instance where the "passenger protection" from the 3hr tarmac rule can effectively force diversions or pre-emptive cancellations. Millions of dollars in fines for each flight at risk. Airline groups did say that would be the unintended result when the rule was being debated.

Frontier wasn't alone... AA370/AS1061, BA6625, AX/US3514, MQ567 diverted with many others late arriving or cancelled within the scheduled TOA 4pm-5pm. Things got worse after that.

Weather and ATC are considered uncontrollable.

Those are probably some good guesses. My friends were trapped at the Akron airport for 5 hours with little to no information being offered other than "storms" - even though as you note the storms hadn't actually reached NYC for most of the time they were waiting.

And yes, Frontier only has a couple of gates at LGA, B1 and B3 I think, so that may have been a factor. I have indeed sat on the runway after landing while waiting for the gate to clear.

The Northeast has a large number of airports and a lot of them with very high E-W and W-E traffic. Picture the normal sky as fenceless wilderness... add a storm like this and it becomes one giant fence with few openings. Effectively choking the system. FAA is pretty good at predicting problems reducing the number of diversions by keeping aircraft on the ground at the departure station.

After thinking about it longer I bet the gate/tarmac delay issue was more likely. F9 decided to route around the problem (very expensive with added fuel) and then possibly realized mid flight a tarmac delay was inevitable. You do have to give the experts that do this some credit... dispatching something like this could have just been solved with a cancellation and your friend would not have arrived albeit late the same day.

So last week I was on a DEN-LGA flight that was supposed to leave before 11AM and once again got weather delayed till around 2:30PM. Yes, it was windy in NYC, however as I and numerous other passengers looking on their phones at flightaware or flighttracker or one of the other apps noted, both a United flight and a Delta flight on the same DEN-LGA route left on time within 10 minutes or so of our scheduled departure (and at least one of them was an A320). So the gate people were repeatedly having to throw up their hands and say they didn't know why Frontier was delayed but United and Delta weren't. Numerous unhappy customers.

They were very clear the order came directly from flight control at LGA. One of the flight crew at first said there was no preferential treatment (his exact words were there's no conspiracy), but after we were delayed a second time he admitted that some of their pilots had complained about this very issue in the past (to no avail).

I suppose the data is available to see whether in fact Frontier is delayed more frequently than other airlines on the same routes at about the same times, but I sort of expect that someone in Frontier management would be paying attention to such things. I mean if I really need to get to NYC reasonably on time on a given day then I might think twice about booking on Frontier.

I understand that LGA is a pit of an airport and extremely susceptible to weather issues, but what I have yet to find is a satisfactory answer to the question of why Frontier is told to wait when other airline's flights are allowed to leave.

In some cases you may do better on Frontier than other airlines - Airbus airlines, at least:

http://www.aviationtoday.com/the-che...l#.URAB56Uii-8

"FAA granted Frontier Airlines operational approval for RNP with Authorization Required (AR) for public procedures in the United States.

Airbus said Frontier Airlines is now the first operator in the United States fitted with Airbus RNP AR 0.3 modification in compliance with the FAA AC-90 101A Approval Guidance for RNP-AR procedures available for applicable airports in the United States.

Frontier Airlines will be able to fly RNP procedures which allow a turn after the Final Approach Point or a missed approach with an RNP values up to 0.3nm. The containment area provided by RNP allows aircraft to fly an optimized horizontal and vertical trajectory in demanding terrain, helps to reduce diversions due to bad weather conditions, lower fuel burn and improve airport access in challenging terrain."

Random chance?

If you are on a Frontier flight that goes out on time despite bad weather, you're not likely upon arriving home to check if the United flight scheduled at the same time was delayed, and then post a congratulatory message onto the Frontier forum Nor would you post on the Frontier forum "Hey, why did your flight get to leave" if you were on the delayed United flight. A couple of pieces of anecdotal evidence does not make for real data.

I looked up the On-Time data from the DOT for all flights from LGA to DEN for 2012: (http://apps.bts.gov/xml/ontimesummar.../src/index.xml). It took quite a long time to load (lots of data I'm sure) but has a ton of statistics. In terms of % of flights delayed, cancelled, diverted, and the delay length, F9 comes out on top of UA on some measures, and UA on others. Neither appears to have a clear advantage, certainly nothing that would point to a vast conspiracy

I would encourage you to visit the site above and draw your own conclusions.

Thanks for that link. I wasn't really interested comparing the overall averages, I was interested in whether my anecdotal experiences of Frontier being delayed more than United (for example) on days with weather issues at LGA was typical or unusual. Direct apples to apples as it were. Although I didn't do a comprehensive examination of both departures and arrivals, and the data provided is not exactly detailed, I think what I did find with a first pass is kind of interesting.

I pulled daily Departure and Delay data for the route I was looking at, DEN->LGA in the approximately 10-11AM time (United was more variable in their scheduled times) for F9 and UA for every day in 2012 for which data was available (335 days, through the end of November). I found that neither carrier used the "extreme weather" code as a cause for delay, so I looked at the NAS (non extreme weather) code. But that sometimes was coded with a longer delay than their overall reported delay, not sure what that means. So I took their overall reported delay time (actual minus scheduled departure times) and subtracted out the other delay categories (carrier-specific issues, late aircraft) to get an approximate "delay related to weather when the plane is actually there" value. (Of course this doesn't include things like sitting on the tarmac.)

To get a sense of the more extreme cases I decided first to look only at delays of 30 minutes or more for each airline. Here's what I found.

In the first 11 months of 2012, United reported 8 such days. Frontier had delays of 30 min or more on 5/8 of those days (63%). Based on a paired t-test, the average delays on each airline on those 8 days were not significantly different: UA Mean=49 min and F9 Mean=37 min (Mean Difference = 12 minutes, p=.29).

Over the same 11 months Frontier reported 31 such delay days, 5 of which (16%) were shared by United. Average delay times were significantly different: UA Mean=13 min and F9 Mean=62 min (Mean Difference = 49 minutes, p<.001).

Based on a chi-square test, the distributions of shared days (5/8 vs. 5/31) were significantly different at p=.001.

My conclusions are: 1) that on comparable DEN->LGA late morning flights, Frontier reported nearly 4x more (31 vs. 8) delays related to weather (not carrier-specific or due to late-arriving planes) of 30 minutes or more than did United; and 2) that the average difference between delay times for the two airlines was 4x longer (49 vs. 12 min) for Frontier on its delay days than for United on its delay days.

As I said, the data are a little messy and the categories broad, and maybe departure time isn't the best metric and etc. etc., *but* overall it looks to me like these data do indeed support my impression. When United had to delay departure at least half an hour due to weather, which happened less than once a month, nearly 4 out of 6 times Frontier had to also. But when Frontier had to delay departure at least half an hour due to weather, which it did roughly 3x/month, United had to do likewise only about 1 out of 6 times.

What remains unclear is the reason for the difference.

Comparing data over time is difficult. It mixes in situations where the aircraft might be in LGA ontime or delayed, Enroute delayed for ATC or other reasons or still on a ground delay at an airport upline. Apples to Oranges especially at LGA.

If say a UA inbound flight was already enroute to LGA and would arrive prior to the F9 aircraft it's departure is more assured to be out of LGA earlier. ATC is pretty good at this. FIFO But every go around creates a very dynamic situation.

Also if in addition to local weather ATC may put an airspace flow program into effect and F9 wasn't willing or able to file a flight plan flying around other weather (more $$ fuel burn) and UA was well that's a different issue.

If you posted the date and flight we could look at it more closely vs the UA flights.

It would be interesting to know where the United aircraft that serves the late morning LGA-->DEN flight is coming from and how long it is scheduled to sit at the gate, versus Frontier. If the United aircraft has more "slack" time scheduled than the Frontier aircraft, that could be an explanation. I have never taken that Frontier flight but I've been on the ~5:30PM Frontier LGA-->DEN flight more than 50 times (used to commute for work) and I know it had a pretty short turn time in LGA.

In my anecdotal experience, while there were almost always delays if the weather was anything other than clear/sunny skies, Frontier always got me back to Denver eventually, even if delayed, and I appreciated the fact that they seemed less likely to cancel than United. This was several years back however and prior to the passenger-bill-of-rights stuff so I don't know if that's led to additional cancellations since.

For today as an example the aircraft comes from ORD and has a little over 2 hours between flights.

I don't see where what I said was not apples to apples. I'm not looking at flights *out of* LGA, I'm looking only at direct late morning flights from DEN *to* LGA. I know there are myriad reasons there may be differences, but I am looking specifically at days when the airlines have reported their delays are due to weather (and not things like the inbound flight is late or something - I filtered those out based on the reported cause of delay information). In other words, in these cases the planes are at the gate and there are no airline-specific problems.

So for some examples, look at 1/30 and 1/31 last week (I looked on Flightaware for this example). The weather in Denver was not an issue, but as is common there were weather delays at LGA. Fair enough, but how were the three DEN-LGA flights scheduled in the 10:00 hour affected?

United 310 (a 757) is regularly scheduled to leave at 10:20AM, and those two days departure times were 10:50AM and 10:55AM. Delta 928 (an A320) is regularly scheduled to depart at 10:50AM - those two days departure was at 1:48PM and 11:23AM respectively. Frontier 510 is scheduled for 10:50AM also (and also an A320) - its departure times for those two days were 3:22PM and 2:23PM.

So, three flights, three airlines, same origin, same destination, scheduled departure times within half an hour of one another, inbound flights not an issue, nothing but the weather (at least reported) as an issue. Yet United was delayed about half an hour each day, Delta was delayed 3 hours the first day and half an hour the other, while Frontier was delayed 4-1/2 and 3-1/2 hours.

Assuming that ATC at LGA is calling the shots as to who leaves when (which is what I was told by Frontier and I have no reason to think that's not true), I'm trying to understand what is the basis for these differences. As I noted in my earlier post, looking at 11 months of daily data for United and Frontier for this route and time suggests these are not random, isolated incidents but reflect a pattern. I found that over 4 times out of 5 when Frontier had a lengthy weather-related delay, United did not. Presumably there is some reason for this pattern, I just don't know what it is.

Interesting analysis (and way more detailed than most of us would be willing to do offhand). Bring it to the attention of Frontier management. They may have not looked at the data on it before. Let them know you'd be willing to accept some extra frequent flyer miles if there is really something there... Or, if they are using weather as an excuse for delays when it is really something else, they may rethink that policy. :-)