Operational necessity

[cjdriver]

Can anyone shed light on why one has to mention "operational necessity" when requesting rwy 19 and the LAS3 sid at KLAS? The original rwy and sid assignment was rwy 25r and STAAV3 sid. Coming out of Atlantic on the northwest side makes for a quick taxi to rwy 19.

 

[Flyin2low]

Because airport policy (managers) have determined that that certain flow patterns are beneficial to the general public. IE. noise abatement. In order for ATC to override that, you have to need the unavailable object for operational necessity.

 

[cjdriver]

Thanks, sounds reasonable. Of course my next question would be; what constitutes operational necessity? Could the shorter taxi fit that requirement due to brake/tire heating, etc?

 

[Flyin2low]

Sure. You don't have to explain it, just request for it. Maybe you need 19 on odd numbered days of the month because of your bosses fear of numbers or something.

 

[rettofly]

Thanks, sounds reasonable. Of course my next question would be; what constitutes operational necessity? Could the shorter taxi fit that requirement due to brake/tire heating, etc?

On those 110 deg days, operational necessity would include the need minimize ground delays to avoid exceeding engine parameters such as oil temp limits. It happened to me a few months ago.
When I told ATC that I might have to shut down an engine to avoid an exceedance, they cleard me for takeoff immediately.