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Is that a displaced threshold leading up to runway 31 at Palo Alto (KPAO/PAO)?
Is that a displaced threshold leading up to runway 31 at Palo Alto (KPAO/PAO)?
No, Palo Alto's runway 31 has a taxiway aligned with a runway.
No, Palo Alto's runway 31 has a taxiway aligned with a runway.
This has a few implications:
- When the tower instructs you to "line up and wait" you should pull on to the runway, which starts at the full-width white runway threshold bar.
- A taxiway aligned with a runway is not supposed to be used for takeoff or landing. (A displaced threshold area, on the other hand, may be used for the takeoff roll).
- But if the tower clears you for takeoff and your are not yet to the white threshold bar you may taxi to the threshold and then commence a rolling takeoff without having to come to a stop.
- The runway available length at Palo Alto is 2443' - that is from White threshold bar to white threshold bar. The taxiway aligned with a runway is 215' long (to the edge of the pavement). And the stopway at the 13 end is 240'. When added together that's 2898' of linear pavement. But the stopway is only to be used to decelerate during a rejected takeoff, or during an emergency. And the taxiway aligned with a runway is only to be used for ground operations.
Shown here is an overhead view of the beginning of Runway 31 at PAO. Notice that the markings in the area leading up to the runway threshold (the big white bar) are yellow, not white. Taxiways are marked in yellow, runways are marked in white. There are some other indications as well that distinguish a taxiway aligned with a runway from a displaced threshold -- see example, below.
Also, note the yellow lines on the edges of the taxiway that are perpendicular to the centerline, outside of the double yellow line taxiway edge markings. These are taxiway shoulder markings. Aircraft must avoid taxiing on the taxiway shoulder since it is not designed to hold an aircraft's weight.
This diagram shows an aligned taxiway preceding a displace threshold. Although this is not the same configuration used at Palo Alto (Palo Alto does not have the displaced threshold) it allows us to see a taxiway aligned with a runway and a displaced threshold in the same diagram so that we can easily see the differences between the two sets of markings.
On the departure end of runway 31 (the arrival end of runway 13) there is a 240' stopway (also known as an overrun area). This stopway is not allowed to be used for normal operation, but it is allowed to be used for decelerating the airplane during an aborted takeoff (aka a rejected takeoff). The stopway is added to the runway length for calculating the accelerate/stop distance available.
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