Serving the Lehigh Valley

2007 QC Fly-in

Project - Queen City Crosswind Runway

The mayor of Allentown has been hoping to close the Queen City Airport. Failing that, he'd like to close half of it and sell one of the runways At least one bid for the land was received. Oddly, the Morning Call's map of the proposal showed development of the land north of Runway 25/7 except the area that the City of Allentown currently rents from the airport authority (cheap rent on space the city uses as a garage and a dump). Suspicious? We think so.

So why would an airport close one of two runways? It's not clear to the LVGAA. Both runways are actively used. One runway is not a spare. It's used to allow airplanes to safely land when the wind is running perpendicular (or near perpendicular) to the main runway. The main runway is the one that favors the wind the majority of the time.

Airplanes need to land into the wind. It slows them down (instead of speeding them forward). If the wind is from the side, it pushes the airplane sideways while it's landing. An airplane needs to approach the runway inline with the center of the runway. You may have noticed that when the wind is from the side, an airplane can be seen to be turned diagonal to the centerline in a crab. While this keeps the airplane traveling along the centerline, the airplane must then be turned facing forward before the wheels touch the ground to prevent stress to the landgear and skidding of the wheels. There is a limit to how much crosswind an airplane can safely tolerate when landing. The following shows the Pilot's Operating Handbook limits of crosswind speeds for typical small aircraft operating at Queen City. Note that this maximum does not mean that pilots can safely land in crosswinds up to this limit. A safe crosswind landing depends not only on the airplane, but the pilot's level of experience and other factors (such as wind speed and direction directly over the runway threshold and gust factors).

  1. Cessna 150 - 12 knots (14 mph)
  2. Cessna 172 - 15 knots (17 mph)
  3. Evektor Sportstar - 15 knots (17 mph)
  4. Piper Cherokee - 17 knots (20 mph)

When an airport has a crosswind runway, this gives a pilot the ability to safely land when the wind is strong in either of the directions perpendicular to the main runway. For local pilots, this means a safer landing if either the wind changes direction or ends up stronger than forecast (which happens quite often!). For neighboring pilots doing flight planning on a cross country airport, this makes Queen City an attractive airport to stop at for refueling or an overnight stay.

The picture below shows the distribution of wind by direction over the period of 1973-2008 as measured at ABE airport in Allentown for the month of July (peak flying month). See other charts here. We overlayed black lines representing the runways at Queen City Airport on the chart. The gray lines indicate the halfway decision points between runways where a pilot would typically choose the closest runway.

cross wind

The following shows aggregated wind direction data for the peak summer flying months of June-July-August, 1973-2008.

  1. Favors Runway 7 - 16.7%
  2. Favors Runway 25 - 32.8%
  3. Favors Runway 33 - 22.0%
  4. Favors Runway 15 - 14.7%
  5. Calm/Variable - 13.8%

By convention, pilots use the main runway (Runway 25) when the winds are calm or variable, we will add those to Runway 25.

  1. Favors Runway 7/25 - 63.3%
  2. Favors Runway 33/15 - 36.7%

So the crosswind runway is useful about one third of the time. To remove this runway would decrease the safety currently available to pilots as well as make the airport less attractive to cross country pilots.