when cleared for a visual...

[avbug]

...what is the min altitude you should go to?

The MSA is 2700', approach has us on a dogleg to final at 3000'. We call the runway in sight and approach clears us for the visual, contact tower. We descend to 2000'. Question came up later as to whether MSA was governing in this situation.

You're on a visual. What has MSA to do with the price of tea in china? You're asking a regulatory question here, or an ethical one?

Minimum safe altitude is an emergency IFR altitude. If one considers MSA in the context of stepping down for a visual approach, it makes no sense. One may have an airfield at 4,000' and a MSA of 11,000'. One can't use a 3:1 for stepping from one to the other, because obstacles may intervene. Therefore, one must do it visually...hence the term "visual approach."

What's the minimu altitude? The altititude at which you can see and avoid obstacles, remain clear of clouds, and see the preceeding aircraft or the airport.

We were not on a published segment of any approach. VMC.

Again, whereas it's a visual approach, being on a published approach or segment thereof is also irrelevant so far as the legality. You're not cleared for any approach procedure; just a visual.

I see what you're saying, and I'm certainly all for flying the published altitudes and procedure whether I'm IFR, VFR, or on a visual. Just for the terrain separation and obstacle protection. However, when cleared for the visual, you're under no obligation to do so, nor expected to do so...and therefore not restricted or bound by any published altitudes. It's a visual. See terrain and obstacles, and avoid them.

Beyond that, as you're visual, but still operating under instrument flight rules, you're bound by minimum IFR (and VFR) altitudes. While both the regulation and your own operations manual will spell out minimum altitudes (and OpSpecs as well, which may be more restrictive than either Parts 91, 121, or 135...such as autopilot altitude loss requirements), you're still bound by each of these requirements to maintain the minimum applicable altitude until required to go lower for landing.

A suggestion regarding generic traffic pattern altitudes has been made...but this isn't in the traffic pattern...and has no more relevance than the MSA. You might consider the type of airspace into which you're operating, which may include, among other things, a requirement to remain above visual or electronic glideslopes. You may consider minimum terrain clearance based on autopilot malfunction altitude losses (eg, 2X the autopilot loss or a thousand AGL minimum, for example; an autopilot having a cruise loss of 600' means that while under your particular authorization a thousand feet might be possible, twelve hundred is the minimum with autopilot). You may consider the presence of higher obstacles and your proximity horizontally to them or vertically above them, congested areas, mountainous terrain, etc. Remember that these still apply as you proceed to the airport, until you need to go lower for landing.

The requirement to remain visual also applies; you've got to keep the preceeding aircraft in sight, or the runway in order to fly the visual approach. If you have to descend in order to do this and can do so legally, then you do as you must, to meet the requirements of the regulation. You're still responsible for your own obstacle, physical, and wake separation (unless you're following another aircraft and can't see the other aircraft).

 

[densoo]

avbug, thanks for the thorough response. In this particular instance, it was not a regulatory concern. It was strictly one of safety of flight. Might we hit something?

I knew one thing--that the MSA guaranteed obstacle clearance. Beyond that, I wasn't so sure. It makes piloting sense (in my mind) that if I'm given freedom to wander about within 25NM of an airport to land, then the MSA is a safe altitude to be at until I've got myself either into the pattern or on final on at 3:1 distance from the runway, in this case about 9 milies.

But several comments here have been right on. I have seen approaches flown when, given the clearance, the pilot points the plane a half mile up the runway centerline laterally, and descends to reach that point at 150', sometimes approaching from a 45 degree angle or more. So you don't reach "a portion of the final" until you're at a half a mile, and my then you're at 150'. Kind of like landing south a DCA. Thirty degrees of bank, roll wings level and flare, sometimes in that order.

Maybe I just overthought the situation. It was VFR, had a visual clearance to runway. See and avoid as someone said.

 

[avbug]

I don't think you've overthought the situation. After all, if you hit something, most would peg it as underthought, if anything.

Certainly you can't go wrong at the MSA. I fly into too many mountainous areas, though, to remain at the MSA until either approaching the traffic pattern, or being right next to the airport...some places that might mean spiraling down from thousands of feet above the field.

My preference, especially where weather might be spotty or questionable, especially at night or in places where I'm not intimately familiar with the obstacles and terrain (and usually even if I am)...I know that establishing myself on a feeder route or overflying the an approach (or requesting clearance for the approach or authorization to follow it where applicable)...I have my terrain separation laid out for me.

When doing rural ambulance work in Nevada,for example, I'd often find myself in garden spots like Tonopah or Winnemucca, usually at night. Even with calling the airport in sight, and a visual received, it still meant descending into terrain. I've spent most of my flying life (and nearly my entire life) in the mountains, and use the lights-in-sight rule for terrain (lights disappear, you may have a problem)...but don't count that good enough to predicate my terrain separation.

With that in mind, I'd plan a higher approach, and descend based both on my knowledge of the terrain, and published altitudes. The MSA at TPH, for example, is 10,500', with the field nearby at 5,300'. This means arriving overhead five thousand feet high...which means either a lot of altitude to lose from overhead...or what I always did at night (regardless of weather)...fly the VOR approach and let down using the procedure turn.

Understandably this isn't practical at many locations...they don't expect you to arrive and simply head out on a cross country excursion with a full procedure turn to get down...and with the visual they want you at the pattern or arrival altitude when you approach the field. You can see how maintaining MSA might be problematic in some locations, then.

Another such place is Bishop, California. It's not too far west of Tonopah, and the MSA there is 15,300'. The field elevation is 4,100'. That means arriving at the field 11,000' overhead, if one maintains MSA until arriving at the traffic pattern. Many nights arriving in Bishop with clear weather, it would be easy to report the field from some distance out. However, there's very high terrain nearby; Bishop is surrounded by the terrain. I always asked for, and received an approach in there at night. During the day, not a problem, unless weather precluded clearly being able to identify and avoid the terrain.

Florida, not so much of a problem, but I've always been far more concerned about those antennas sticking up in Florida than I am about the valleys sticking down in the mountain west...or the hills that poke up between them. It's probably an old ag habit, but wires and towers concern me a lot...mountains and big hills are easy to spot. Towers, not so much. You're right to be concerned about them jumping out of a cloud or popping up where you least expect.

I've heard some wild ideas about predicating a letdown on EGPWS, or in former times, those who did it based on radar. I'm not a big proponent of either of those choices (though I have used radar with good effect while passing overhead Bishop on the way into Lone Pine...radar paints the hills on either side very clearly when flying that valley at night).

It's not always practical to ask for an approach, and in busy areas it can really interrupt the traffic flow of visuals are in proress and the lineup is packed. It's also not always practical to fly MEA to MSA. Sometimes you can obtain MVA, but that can be sporadic and segmented, and unless the controller is assuming terrain separation it may do you little good. You do have the option of not calling the airport in sight too soon, or of admitting lack of familiarity with the area; either is perfectly legitimate. In any event, if the visual is accepted, then see and avoid is still the rule for traffic and airplane parts alike.

You're not overthinking it at all...after all the fundamental question is how to get down safely, and it's just as legitimate for a visual approach as any instrument procedure.

 

[densoo]

Sounds like you have an interesting job. I don't see visuals a lot, especially as the only one on arrival and 15 - 20 miles out. Leads to cobwebs I guess.

 

[tomgoodman]

Thanks

Very informative posts! One of the benefits of forums like this is learning about varieties of flying outside our usual experience.