I apologize in advance for how dumb this will likely sound:

I have seen some dual parallel approaches in which (in rough terms) one plane turns left and another plane turns right before aligning with the runways (which have an appropriate separation for independent parallel approaches), like in diagram to the left:



So my questions are: If there's an unavoidable obstacle like mountains, it is possible for both planes to follow a path that involves turning right before aligning with the runways? (like in the diagram to the right)

If it is possible, what would be the consequences in the total capacity of the runways? (for example it could disable independent parallel approaches?)

There's some ICAO or FAA manual addressing this scenario?

Thank you in advance.

In addition to lateral separation while vectoring aircraft onto the final approach course, aircraft on approach to different runways are kept at different altitudes when joining final. For example aircraft vectored to join the left runway join at 5000 feet, while aircraft vectored to join the right runway join at 4000 feet.

Or in instances of the parallel runways, the center runway joins at 5000 feet and the outer runways join at 4000ft for example.

Actually, it’s probably done more because a portion of the traffic is arriving from a particular direction. For instance, KFLL or KMIA, most domestic arrivals are from the north. ATC will separate them, as Woodreau noted, by altitude at the course intercept and longitudely by track miles from the runway.

GF

The correct term is Independent Parallel Approach

Woodreau wrote:

In addition to lateral separation while vectoring aircraft onto the final approach course, aircraft on approach to different runways are kept at different altitudes when joining final. For example aircraft vectored to join the left runway join at 5000 feet, while aircraft vectored to join the right runway join at 4000 feet.

The higher one often is only cleared to join the LOC, and only cleared for the ILS once the lower one is established.

T54A wrote:

The correct term is Independent Parallel Approach

With all respect, the correct term in within the U.S. is Simultaneous Dependent Approaches (FAA JO 7110.65X, Para 5-9-6) where the controller is required to maintain a 2NM stagger between arrivals. This is based upon runway center-lines are at least 2,500' apart and no more than 3,600' apart.

In order to conduct Simultaneous Independent Approaches Dual/Triple there are a number of things which must be met, but a minimum of 3,900' between runway center-lines and the airport elevation is 2,000' MSL or less for starters. They are fun to control as a final controller because in essence as long as the other final controllers are doing things correct with the turn on altitudes you don't have a stagger involved with the other runways, so rock and roll!

zeke wrote:

Woodreau wrote:

In addition to lateral separation while vectoring aircraft onto the final approach course, aircraft on approach to different runways are kept at different altitudes when joining final. For example aircraft vectored to join the left runway join at 5000 feet, while aircraft vectored to join the right runway join at 4000 feet.

The higher one often is only cleared to join the LOC, and only cleared for the ILS once the lower one is established.

Not necessarily. If the approaches are built correctly they will have step down fixes with differing altitudes for each runway.....so "Gulfstream 222A cross BINGO at or above 4,000, cleared ILS/RNAV Runway 26L approach". The step down fixes ensure the 1,000' of altitude separation so you don't have to make another transmission to issue the approach clearance.

Woodreau wrote:

In addition to lateral separation while vectoring aircraft onto the final approach course, aircraft on approach to different runways are kept at different altitudes when joining final. For example aircraft vectored to join the left runway join at 5000 feet, while aircraft vectored to join the right runway join at 4000 feet.

Or in instances of the parallel runways, the center runway joins at 5000 feet and the outer runways join at 4000ft for example.

That is correct if you are only operating with dual runways, if Triple approaches then you must use 1,000' vertical separation between all three runways. Example....lowest turn on altitude is 2,000' which would be an outboard runway then the other outboard would use 3,000' while the middle runway is 4,000' or above when intercepting the final approach course.

It gets crazy with all that the controllers must consider before starting dual/triple approaches, but it all works out great when aircraft are at the proper intercept altitudes.

Thank you for your responses.

The real reason I made those questions is because the incoming Mexican government wants to scrap the new Mexico City airport already under construction (having triple independent approaches) and instead convert Santa Lucia AFB (NLU) into a civilian airport and keeping the old MEX open.

They propose those approach paths:




So, do you think NLU will be able to operate Independent Parallel Approaches with a 90 degree turn just before the Lucia4 waypoint (which seems to be around 4 NM from the runways)?

They don't seem to consider any vertical separation for both approaches to NLU (LUCIA1 and LUCIA2).

IAHFLYR wrote:

T54A wrote:

The correct term is Independent Parallel Approach

With all respect, the correct term in within the U.S. is Simultaneous Dependent Approaches (FAA JO 7110.65X, Para 5-9-6) where the controller is required to maintain a 2NM stagger between arrivals. This is based upon runway center-lines are at least 2,500' apart and no more than 3,600' apart.

In order to conduct Simultaneous Independent Approaches Dual/Triple there are a number of things which must be met, but a minimum of 3,900' between runway center-lines and the airport elevation is 2,000' MSL or less for starters. They are fun to control as a final controller because in essence as long as the other final controllers are doing things correct with the turn on altitudes you don't have a stagger involved with the other runways, so rock and roll!

Why is there a field elevation limitation? Does this preclude using Simultaneous Independent Approaches at DEN? I was under the impression that a big reason for DEN being designed with such widely separated parallel runways was to allow for those type of operations. Thanks for all the interesting info!

LU9092 wrote:

Why is there a field elevation limitation? Does this preclude using Simultaneous Independent Approaches at DEN? I was under the impression that a big reason for DEN being designed with such widely separated parallel runways was to allow for those type of operations. Thanks for all the interesting info!

There are so many different situations with airports and requirements for dual/trips independent approaches, Some require special RADAR equipment for monitoring the finals or offset approaches specially designed for max efficiency. Denver has the ability for the approaches, not certain any longer since I retired, but they may have to have in the TRACON special high up-date RADAR...sorry wish I could completely answer that for ya...maybe a DEN controller will help out with a more complete answer.

There are so many i's to dot and t's to cross it will make your head spin and I've probably got something bassakwards with the distance between runway center-lines as without special RADAR and/or studies the norm was 4,300' for dual and 5,000' or more for trips.

Here take a look at this and see how your head feels after starting at Para. 5-9-5.

https://www.faa.gov/documentLibrary/med ... ontrol.pdf

IAHFLYR wrote:

Here take a look at this and see how your head feels after starting at Para. 5-9-5.

https://www.faa.gov/documentLibrary/med ... ontrol.pdf

Wow, I'll let you know when it stops spinning. I did see this, which partially answers my question:

NOTE−
Airport field elevation requirement does not apply to dual parallel runways that are 4,300 feet or more apart.

Thanks again!

LU9092 wrote:

Thanks again!

KrustyTheKlown wrote:

The real reason I made those questions is because the incoming Mexican government wants to scrap the new Mexico City airport already under construction (having triple independent approaches) and instead convert Santa Lucia AFB (NLU) into a civilian airport and keeping the old MEX open.

They need a 4000+ meter runway for long haul flights.the new MEX has multiple 4500 and 5000 m runways.