They do it by taking planes off the RNAV routes and do the old fashioned vectoring.
Why would you assign a SID
that everyone knows the pilot cannot fly due to weather? With a radar vector SID
, the controller has far more flexibility in tweaking the flight path in good or bad weather as well as finding short cuts when traffic permits. If traffic does permit, nothing is stopping an ORD
departure from an unrestricted climb. With RNAV SIDs you have a pre-determined route and pre-determined climb points etc...very conservative and not necessarily the most efficient. Much like driving a 6-lane freeway and not being able to change lanes even though another lane might be faster.
Chicago has about 25 satellite airports in area that need to mix their traffic into the ORD
flow as well. This requires a lot of s-turning, speed adjustments and altitude step-ups in the departure areas which would also make the RNAV departures ineffective in many cases.
With the vector SID
, the controller can vector the flight over the exact same route the plane might fly on an RNAV SID
but he'd be much more likely to find a short cut. I don't know if the ATL
departure guys do much vectoring on departure or if they mostly leave planes on the SIDs.
|Quoting apodino (Reply 49):|
Again, with the need of departures to avoid the missed approach areas
You're not protecting for missed approaches in VFR weather...you're avoiding the areas where the arrivals descend from 7,000' on the downwinds. Go-arounds and missed approaches are dealt with on an individual basis as separation standards are different.
Instead of suggesting that ORD
go to RNAV SIDs, why not suggest that ATL
go to a vector SID
? Tunneling might not be the most efficient for an individual aircraft but the procedures at ORD
are set up to be the most efficient for the overall operation and not individual aircraft. Arrival capacity has always been the biggest challenge for ORD
and the procedures are built around optimizing that part of the operation. Everything else is built around the arrivals out of necessity.
|Quoting N353SK (Reply 50):|
Common sense says that as a pilot paid by the minute I'm probably better off waiting two minutes than trying to figure out where on the runway I'm going to become airborne.
No one is suggesting that pilots should always request a waiver but it's an option that is available that many might not be aware of. If you're making decisions on how you operate your aircraft based on your paycheck, I have nothing left to add.