I was on an IFR flight plan in VMC. The ATC asked me what approach I wanted, and I said visual approach. He said expect RNAV approach instead without saying why. I wonder if it's okay to ask for vectors for visual approach when you are still far out and have no visual yet, or it's expected to ask for an IAP first and then ask for visual when you have the field in sight? Thanks!
The answer to this question really has to do with shared expectations between pilots and controllers with regards to workload. Let’s consider two scenarios:
Before the field is in sight – (your question) As an instrument rated pilot, on a filed flight plan with an appropriate equipment code, ATC expects you to be capable of following a published approach procedure to navigate yourself to a position from which you can make a landing. If you are asking a visual approach before you are in a position to accept it, (i.e. need vectors) you are in essence telling the controller that you are either unable, or just don’t feel like doing so. Instead, you want them to do the work for you to get set up on final.
Workload permitting they may be happy to oblige, or they may vector you anyway for separation, but they are not required to navigate for you. However, if you have an equipment malfunction you are required to let them know, and declare “unable” for any approach they might try to clear you for that you cannot comply with.
Field/Traffic in sight – In this case the controller might look favorably upon your request because visual approaches put some responsibility for maintaining separation on the pilots. (if you report the traffic you are following in sight you are required to maintain adequate separation from it, not ATC.) This may help them out some, and they would really have no reason to deny you the approach request. But if for any reason they did deny the visual, you would have two options:
- Just continue to fly the published approach you were cleared for. Once you are VMC with the field in sight you will have met the criteria for descending below published mins, so there is really nothing stopping you from proceeding by using primarily visual reference at any time after that. Just make sure you continue to monitor the instruments for guidance. And to the best of your ability it would be wise to continue to comply with all procedure altitudes, VDP, etc. (FYI, most airlines require pilots flying a visual approach to have an instrument procedure loaded and to use it for guidance.)
- Cancel IFR. Switching to a visual approach while still on your IFR clearance really serves no purpose once you have the field in sight. And if you fly IFR into untowered airfields on a regular basis, it might be a good habit to get into canceling IFR airborne as soon as you have the field in sight to prevent forgetting to call and cancel your flight plan after landing.
In short, by requesting a visual approach before you have the field in sight you are making more work for ATC, (making them less apt to clear you...) but requesting or accepting a visual after the field is in sight you may be helping them.
I had an afterthought... If you don't want to be bothered loading, activating, flying a (possibly complex) approach that you have no need for and don't really want, yet you want to remain on your IFR clearance, there is an option other than asking for vectors. Look at the approach and pick out a waypoint or two that will roughly sequence you for arrival as if you were flying the published procedure, and that will put you in a good position to see the runway. (say a 5-10 mile straight in) Then make a request to fly direct at your current (or some other) altitude for a visual final. That way you do the navigation, ATC isn't burdened with vectoring you, and you still get the approach type you want.
You - "N123Y request present position direct CHUNKS at 3000' for visual approach RW 16."
ATC - "Cleared direct CHUNKS at 3000', you can expect the visual, report field in sight."
You - (when there) "Field in sight."
ATC - "Roger, cleared visual approach RW 16."
ATC is generally pretty good about trying to give you what you want as long as you are clear in the way you are asking it. They know when the weather is beautiful, and why you might not want to bother with a full instrument approach. And understanding what you want, they might even offer a compromise based on MVA in different sectors, i.e. "Unable direct CHUNKS at 3000', can you accept 4000' to PUKE, then 3000' to CHUNKS for the visual?"
It's perfectly fine to request a visual approach before you have visual reference, just make it clear that you are not ready for the approach yet ("Request visual later on" or something).
ATC may still assign you another type of approach if a visual does not fit in the traffic picture.
Typically the type of approach to expect is noted on the ATIS (e.g., ILS, RNAV, Visual [including Charted Visual Flight Procedures -CVFP). It's OK to request an approach not being advertised on the ATIS or the approach you are told to expect by ATC on initial contact with the approach controller (e.g., TRACON).
Often the traffic flow requirements to the runway(s) in use reduces or eliminates the controller's flexibility in letting you fly a different approach than the "approach in use." But you can always ask.
If the ILS is in use, for example, if flying a Visual Approach at a busy airport the controller will likely vector you to final anyway to establish the appropriate sequence and spacing the Tower needs.
Also for CVFP's the weather minimums are often higher than for a regular Visual Approach and may disallow the use of that approach.
Again, you can always ask.