WEATHER IMPACTS ONAIRPORT OPERATIONS

DUSTIN HARBAGE

Lead Forecaster NWS Jackson, KY

Airline Rated Pilot

11/14/01

•Operations vary at airports due to weather conditions.•As weather lowers from VFR to LIFR the options available to controllers change and become more limited.•These reduced options require increased separation between aircraft and hence fewer aircraft takeoffs and landings per hour.

Airport Operations

There are several critical altitudes in and around the airport.

Each airport is different based on:Available runwaysAvailable approachesRunway configurationTraffic densityNoise restrictions

Critical Altitudes

Airport information

Plan View

Side view

Approach Minimums

Frequencies

Airport diagram

Airport Elevation

Pattern Altitude

Wichita, KS

Notice that Chicago has three (3) sets of parallel runways!

The most obvious and least restrictive weather for an approach would be VFRHere aircraft can be sequenced in for landing

as soon as they can identify the preceding aircraft.

This may be before they can see the airport, as in the case of LAX.

If the weather goes below VFR but remains above the Final Approach Fix altitude then the aircraft can be vectored to a point where they can located the airport and/or the preceding traffic.

If the weather goes below the Final Approach Fix altitude but remains above the traffic pattern altitude. Aircraft can be vectored to a point where they

can safely enter the traffic pattern and complete a visual pattern and landing (If one is available).

Each individual aircraft would supply their own separation from preceding aircraft.

When the weather decreases to below pattern altitude then instrument approaches must be flown.Separation from preceding aircraft is provided

by approach control.The type of approach is determined by:

Approach availability, Aircraft instrumentation, Pilot certification,and Weather.

When an airport has multiple runways it has other operational options.It may sequence aircraft towards intersecting

runways with timing separation to keep them from arriving at the intersection simultaneously

If parallel runways are separated by 1 mile or more then they can use a staggered approach sequence.

If parallel runways are separated by 3 miles or more then they can use simultaneous approaches.

The major factor for an airport is that no two aircraft can be on the same runway (even at different ends) at the same time.

Sequencing aircraft for arrival or departure is based on being able to get one aircraft off the runway before another touches down or begins a takeoff roll.

The lower the weather the greater the separation required between aircraft to achieve the one aircraft per runway rule.