Monday, December 24, 2007


For those that are just joining us, I’m peeking into the corners where the FAA sweeps their data about airport capacity. The FAA is, of course, a public institution and is expected to tell the truth about various matters. And they do, if you know where to look and how to read “governmentese.” I’m not an expert at either, but I have some practice and I’m more stubborn than most.

Today’s subject is LaGuardia (LGA). Named after new York’s famed mayor, Fiorello LaGuardia, at various times, LGA has been described as the world’s greatest airport all the way down to the bleak, LaGarbage.

Speaking of garbage, let’s look at the numbers from the FAA’s
Airport Capacity Benchmark Reports for 2001 and 2004.

In 2001: ”The current capacity benchmark at New York LaGuardia is 80-81 flights per hour in good weather. “

In 2004: ”The capacity benchmark for New York La Guardia Airport today is 78-85 flights per hour (arrivals and departures) in Optimum weather, when visual approaches can be conducted. “

Once again, we seem to be losing capacity. Or is it gaining ? It’s so hard to tell.

In 2001: ”Current capacity falls to 62-64 flights (or fewer) per hour in adverse weather conditions, which may include poor visibility, unfavorable winds or heavy precipitation.“

In 2004: ”The benchmark rate is 74-84 flights per hour in Marginal conditions, and 69-74 flights per hour in IFR conditions, for the most commonly used runway configuration in these conditions. Throughput may be less when conditions force the use of other configurations. “

Aha ! A ray of hope. An improvement in IFR conditions. From 62-64 in 2001 to 69-74 in 2004. Tsk, tsk. Come, come people. This is governmentese. You have to read the whole thing. ”Throughput may be less when conditions force the use of other configurations. “ The 2001 stats didn’t make any such disclaimer. I’m assuming it was an average “throughput”, considering all “configurations.”

As far as truthiness (copyright 2005 -- Stephen Colbert), I’d have to go with the 2001 report.

” • LaGuardia operates close to its good-weather capacity for nearly 8 hours of the day, but these traffic rates cannot be sustained in adverse weather.

• In 2000, LaGuardia had the highest rate of delays in the country. Over 15% of all flights at LaGuardia experienced significant levels of delay (more than 15 minutes). Average delays vary from 47-52 minutes in both good and adverse weather.

• In good weather, LaGuardia’s scheduled traffic is at or exceeds capacity most of the day.

• In adverse weather, scheduled traffic exceeds capacity 12 hours of the day. “

Oh, and this last line.

”• This data does not reflect the effects of the slot lottery that took effect recently, on February 1, 2001.“

I have to say, though, when it comes to truthiness (copyright 2005 -- Stephen Colbert), the 2004 report is not without its charms.

”In the following charts, please note that a number of hourly traffic points fall outside the calculated capacity curves at LGA, especially in IFR conditions. There are many possible reasons why this may occur without affecting operational safety, including efficient sequencing of aircraft and above-average controller and pilot performance. Also, actual weather conditions during the hour may have been better than the hourly readings in the database, allowing more efficient ATC procedures than were modeled. “

(emphasis added)

Say what ? Controller and pilot performance is recognized in an FAA capacity report ? Holy Smoke ! That doesn’t bode well for the immediate future does it ?

As I keep saying, there is a finite amount of capacity for any runway. It doesn’t get any better until we change the rules. Most of the rules are safety rules and they won’t be changed.

Once you accept that “benchmark” -- that truth -- it’s all downhill. There are a myriad of factors affecting capacity but all of them take away from the maximum number. Less controllers equals less capacity. Less talented controllers equals less capacity. Some of my sharper readers may have noticed that LGA’s capacity isn’t that much lower than JFK’s which is kind of strange considering the runway layouts. (LGA and JFK) It’s hard to explain the type of traffic JFK handles and its effect on capacity -- in 800 words or less. Or in a nontechnical way. Or in a culturally and politically sensitive way. JFK handles a lot of overseas flights -- lots of “heavy” aircraft that require additional spacing for wake turbulence and being flown by pilots to whom English is a second language. A lot of things take away from the maximum capacity of a runway.

Don Brown
December 24, 2007

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