"Cleared visual approach, descend altitude 2000ft"

[notdavegorman]

Hello ATC people.

I regularly fly the B737 into a regional UK airport, often if Wx & traffic conditions allow, we will often request a visual approach whilst on base or downwind leg.

Our ops manual states a visual approach will be conducted with visual separation from the terrain (by us), however ATC will still prove IFR traffic separation.

On one occasion recently, we requested and were cleared a visual approach, however we were also cleared to descend to 2000', which happened to be the MSA, in the same reply.

As far as I know, the reason for the altitude restriction wasn't due to traffic, as we weren't passed any traffic information, we didn't have any TCAS contacts on our displays and in any case, surely if there was a potential traffic conflict, the controller should have at least delayed clearing us for a visual approach and kept us under vectoring.

As we pilots become responsible for terrain separation, my question is why else would an descent clearance be placed on us once we've been cleared for a visual approach?

[I ask because the only reason we fly a visual approach if an instrument procedure exists is to expedite proceedings, so our natural inclination is 'cut it in tight' and fly the most direct track we can towards the runway as long we're stabilised by 500' AGL, that is to say on speed, on glide and on our final approach track, wings level. Having such a descent restriction kind of throws a spanner in the works...]

[Dr Esteban]

Some ATCOs clear an aircraft for a visual approach in the following manner:

"ABC 123 cleared visual approach, do not descend below altitude 2000 feet until established on final". (another way of saying "cleared visual approach, descend altitude 2000 feet")

This could be due to noise abatement, avoiding aircraft to turn in too tight and avoid overflying noise sensitive areas. Indicating that you do whatever you like, but descending below 2000' should be done on the centreline, with the nominal glide-path. Ie a different way of saying "aim for a 7 mile final" (in the 2000 feet case).

Dr.

[spekesoftly]

Could it have been a temporary altitude restriction to ensure you remained above the base of controlled airspace? If so, ATC were simply complying with CAP 493.

[chevvron]

At my airfield, the visual circuit altitude downwind is 1700ft; you're not supposed to go below that until you turn base. That could be the case here with a 2000ft minimum downwind.
You say 2000ft happened to be MSA, but how does that compare with the minimum altitude on the radar vectoring area chart in the position you were?

[AlanM]

At LCity we have to come out with this diatribe....

"Cleared for a visual approach runway 28, to join the final approach track not less than 5 miles from touchdown - not below 3000 feet until 6DME"

(Due noise and CAS base)

Sometimes easier to vector them onto a standard 7 mile final!

[VCR]

Cut and pasted from the Manual of Air Traffic Services

10.3 Visual Approach
When an aircraft is cleared for a visual approach the clearance must include, where
necessary, a level restriction to ensure that:
a) the aircraft remains within radar cover; and
b) the pilot does not descend below the base of controlled airspace.
10.4 Final Approach
10.4.1 Aircraft on radar approaches should be positioned so as to maintain a period of level
flight before commencing descent on:
a) the nominal glide path for a surveillance radar approach; or
b) the glide path of a pilot interpreted approach aid;
except in an emergency or when continuous descent approach procedures are in
operation.
10.4.2 Aircraft should be vectored to close the intermediate and final approach tracks at not
less than 5 miles from touchdown.

[catocontrol]

Originally Posted by spekesoftly

Could it have been a temporary altitude restriction to ensure you remained above the base of controlled airspace? If so, ATC were simply complying with CAP 493.

Correct. In Norway at least, it is the ATCo's responsibility to keep the a/c in controlled airspace

[Dr Esteban]

You say 2000ft happened to be MSA, but how does that compare with the minimum altitude on the radar vectoring area chart in the position you were?

Neither MSA or minimum radar altitude should be an issue. On a visual approach you should be VMC and therefor you are allowed to descend below both MSA and radar minima.

Dr.

[10W]

Neither MSA or minimum radar altitude should be an issue. On a visual approach you should be VMC and therefor you are allowed to descend below both MSA and radar minima.

But not below any altitude restriction published in the AIP. Many UK airfields (as some have said for specific examples) have a 'do not descend below xxxx feet until established' restriction. That seems to be the best bet in this case. Name the airfield and it will be easy enough to check in the AIP

[LN-ATC]

Originally Posted by catocontrol

Correct. In Norway at least, it is the ATCo's responsibility to keep the a/c in controlled airspace

According to which document, Cato?

[Pierre Argh]

Regional airport... but many of the replies allude to CAS, which a lot of those fields do not enjoy? Are you talking UK (you'd be amazed how different the rules can be, and must take that into account when reading any replies!)

Overlooking CAS, in unregulated airspace a visual approach should IMHO count as a VFR procedure... under which the pilot is, not only responsible for terrain clearance and separation from other VFR traffic? A restriction on a VFR approach (as quoted) might be to ensure separation on IFR traffic in the vacinity, as well as noise abatement etc etc?

[Chilli Monster]

Originally Posted by Pierre Argh

in unregulated airspace a visual approach should IMHO count as a VFR procedure...

I'll disagree with that. In unregulated airspace there is no requirement to separate IFR from VFR anyway. There is, however, a requirement to separate IFR from IFR if they have put themselves under the control of an Approach Control Unit (which they will have done).

So - taking the above into account - You have a gin clear day, 3 or 4 IFR inbounds, all wanting Visual approaches. They haven't uttered the phrase "Cancel IFR" so, iaw MATS Pt.1 you still have to sequence them in such a way that, although they may be approaching visually, IFR separation is not eroded. In short - you cannot treat it as a VFR procedure with all that entails.

[Spitoon]

under which the pilot is, not only responsible for terrain clearance and separation from other VFR traffic

But normally no-one separates anything from VFR traffic in that type of environment. Be careful not to confuse collision avoidance and rules of the air with separation.

Sorry Pierre but I don't think you're up to you normal high standard with that post.

[almost professional]

Normal technique at Nema is to clear for the visual, but add a not below level-usually 3000ft-depending on the position of the inbound relative to the field, this allows the Apc controller to
A:co-ordinate with the tower to ensure they have no traffic to afffect
B:ensure the inbound does not leave controlled airspace
C:comply with noise abbatement procedures
sounds like similar procedure

[Pierre Argh]

Spitoon thanks for the veiled compliment... your's and Chilli's interpretation may well be right. I agree wholeheartedly that IFR/IFR requires separation and that VFR/VFR separation is the pilot's responsibility not ATC... as usual we come to the difficulty in the IFR/VFR area?

Without wishing to get bogged down in that; I agree that, technically speaking, a pilot that requests a Visual Approach need not be VMC or unwilling to cancel IFR. But this is all the more reason to place an altitude restriction on a visual approach, as we are now starting to move into that other notorious grey area relating to Terrain Clearance and ATC instructions?

I suppose you could get out of this quagmire by saying, "Continue VFR, Visual approach approved"?

[Chilli Monster]

Originally Posted by Pierre Argh

I suppose you could get out of this quagmire by saying, "Continue VFR, Visual approach approved"?

That's a no-no too. Pilots can cancel IFR, we can't tell them to (or even ask them if they want to).

To be quite honest, Rules of the Air take care of it anyway. After all, provided you are below 3000ft, clear of cloud and in sight of the surface the minimum height rule ceases to apply, therefore there's nothing to prevent you being IFR below MSA providing you are in VMC. Terrain separation is then - by definition, pilots responsibility.

[catocontrol]

Originally Posted by LN-ATC

According to which document, Cato?

The secret one

[catocontrol]

Demand from CAA

Well I don't remember where I read it, but I do know that it is a demand from the norwegian CAA

[notdavegorman]

All, thanks very much for your ideas.

Going back to my original query, I think the reason for the 2000' altitude restriction on this occasion was due to a noise abatement restriction. Due being vectored off our normal track, we commenced our visual approach from a rather different position than is normal, and our track took us straight over a large conurbation, hence the unexpected clearance.