Strange LGA Taxi/Departure Activity (7/1/06)

[PhilDernerJr]

Though the days' ops were up and down 22, several United 737s taxied to the far side of the runway near the Marine Air Terminal, sat there forever, then departed on 4.

Why would they depart on 4 with a tailwind just to turn around in the direction the planes were departing anyway? I figured they were going to Chicago, and it jsut made no sense.

I also saw a US aircraft do the same.

Anyone have any idea?

[LGA777]

Even with a tail wind you often get a higher max takeoff weight off 4 and 31 due to the lack of obstructions at the end of runways unlike 22 and 13. The high temperatures of summer make what Phil saw a fairly common occurrence, usually if landing 22 and departing 13, the very heavy traffic will depart 31. This procedure could in some cases add up to 5000 lbs of payload to a 737 for Fuel, Passengers, and or Cargo.. The delay this can cause a flight after leaving the gate can vary between 10 extra minutes and several hours !

Regards

LGA777

[USAF Pilot 07]

Yea but the tailwind increases takeoff distance. If a plane is close to weight and if the calculated takeoff distance is close to the length of the runway, there's no way that plane would opt to takeoff in a tailwind....

If the planes were UA737s chances are they were going to ORD. No way they have a full fuel payload, and I would think that they would have most certainly been able to lift-off of 22 at LGA without being close to "obstructions" at the end of 22...
As for 13, if you takeoff of 13, there are no obstructions at the end of the runway, just the water....

I don't understand it either...

[LGA777]

USAF Pilot, not to be a jerk but since you are disputing a lot of what I said in my reply to Phil D I was curious how much actual operating experience and knowledge of Air Transport Aircraft weight and balance experience and knowledge you have ? I asked that because prior to my airline centralizing it 's weight and balance work I personally did the weight and balance on "THOUSANDS" of flights out of LGA with hundreds of them requiring an alternate runway for departure. Aircraft included McDonald Douglas MD-80 and DC-9-30, Fokker F-28 and F-100, and Boeing 757-200, 727-200, 737-400,300 and 200. With each and every one, SAFETY, was first and foremost my and the companies NUMBER ONE Priority !

And by the way Runway 13 is the "Most" restrictive runway at LGA due high rise buildings and a large church steeple in Flushing.

Respectfully,

LGA777

[USAF Pilot 07]

LGA, I'm not disputing any of your point directly, I just didn't really understand your post well.
I don't understand when you said "even with a tail wind you often get a higher max takeoff weight off of 4 and 31 due to the lack of obstructions at the end of runway unlike 22 and 13"...
If I imply your post correctly, you're saying that takeoff weight is a function of which runway is being used, which makes no sense..
Are you trying to say that permissible max takeoff weights are greater when departing runways 4 and 31 because of the lack of obstructions?
I know how takeoff distance is calculated; a function of Pressure Altitude and OAT, A/C weight, headwind/tailwind strength, and height of obstructions beyond the runway, so this would seem to make more sense.

What I don't understand either is why if the plane was a UA737, most likely bound for ORD, it would be too heavy to use 31 or 22, especially since a ton of other 737s were able to use that runway for takeoff, probably weighing the same or more than the UA737. Is it a company policy thing?

And one last thing. I can understand the obstructions at the end of RWY22 playing a factor in calculated T/O distance, but the obstructions off of RWY13 - the buildings in Flushing you mention - are something like a mile away. How do those play any factor in T/O distance calculations, especially since those should be no factor at all to T/O unless you have a serious problem?

As far as tailwind goes, if your max takeoff distance is approaching runway length, wouldn't it be more sensible to use the runway with a headwind than a tailwind, especially if the tailwind briefly gusts or picks up during your T/O roll? I would think it'd be better to be airborne than to not get off the ground....

[DHG750R]

Guys,
Ron is correct . I can personally vouch for this as for many years we both have performed many , many weight and balances on several narrowbody types including DC9's MD80's , B737-2/3/400's Fokker 28/100's . LGA has very big climb penalties departing runway 22 / 13. Runway 22 is by far the worse. The restrictions are during the 2nd stage climb Example. with some aircraft the difference between runway 22 and runway 4 can be as much as 4-5000lbs. this of course can mean the difference between a profit and loss . either thru leaving some pax behind and or leaving their bags . It can also mean the difference between a fuelstop enroute or a diversion at the end of the flight .

Now of course it isnt this simple , there are several other factors to come into play as you've added. temp , winds and barometer settings , runway slope . etc . When the runway length requirement exeeds any obstacle climb weight. The runway performance becomes the limiting factor ( the case of runway 4 ) However when the climb performance exceeds the runway length requirement .. then it is controlling.

In most cases , not all there is a benefit to using runway 31 of 4 even with a small tailwind. Remember the maximum tailwind component is 10kts

The 757 is by far the best aircraft . It generally has one set of numbers no matter the runway or temp at LGA

The important thing to remember is here we are planning a takeoff with the mindset the most critical engine will fail after V1.

[PhilDernerJr]

Also, I saw a Delta MD-80 depart on 22 so low that it literally was as low as many of the rwy 4 arrivals over the Grand Central Parkway.

[PHL Approach]

Phil, when you saw this happen. Do you remember what Kennedy was running?

[727C47]

we are severely performance limited out of vegas to detroit in the 727-200,we have sweated out many a performance calculation that had us within ounces of the runway limit, its just no fun out there when its 107 F,and the runway of choice is sporting a 4 kt tailwind, lots of times it just doesn't work,we take less gas,and make a tech stop for fuel on the way east.

[DHG750R]

Thanks for reminding me .. The 727 was very interesting for us at LGA as well . in fact a big part of the runway 22 penalty was for noise , the rest for the climb performance , or lack thereof. The benefit of a non-standard runway could've been as much as 15,000lbs when we used it on the LGA-BDA trip where the closest alternate was usually ORF which is almost 90mins away

Definitely not a knock on the aircraft .. in fact I love the 3 holer :)