Aircraft on approach to SEA are descending at a 3-degree angle to the runways. This is the standard approach angle for landing aircraft at U.S. airports and has not changed. The exception is the approach to Runway 34R, which is set at 2.75 degrees to the runway.
Departing aircraft altitudes are generally determined by aircraft performance. Larger, heavier aircraft with full passenger and cargo loads sometimes have a slower climb rate, meaning that they may be flying lower than smaller aircraft using the same route
