Speed control on a Visual Approach at night
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Speed control on a Visual Approach at night
Say it's completely VMC (at night) - you can see the lights of the town near the aerodrome from over 50nm away, but the runway itself has no VASIS/PAPI (I experienced this the other night going into Moree).
Technically to conduct a visual approach in this situation (IFR) you need to be inside the circling area before leaving the MSA/DGA step. In your opinion does this mean at night you're effectively in IMC until inside the circling area and therefore need to comply with speed restrictions for Instrument Approaches (eg max and min Initial and Final Approach speeds)? I tracked via the RNAV to allow a straight in approach and think speed control should be the same as if you were conducting the approach in IMC, but have heard others disagree and say there shouldn't be any restrictions on speed.
Just keen for people's ideas/any other situations you've experienced like this where it's a bit of a grey area!
Technically to conduct a visual approach in this situation (IFR) you need to be inside the circling area before leaving the MSA/DGA step. In your opinion does this mean at night you're effectively in IMC until inside the circling area and therefore need to comply with speed restrictions for Instrument Approaches (eg max and min Initial and Final Approach speeds)? I tracked via the RNAV to allow a straight in approach and think speed control should be the same as if you were conducting the approach in IMC, but have heard others disagree and say there shouldn't be any restrictions on speed.
Just keen for people's ideas/any other situations you've experienced like this where it's a bit of a grey area!
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Need to recognise there's no difference to an instrument approach whether you're VMC or not. The only difference is that if you can meet the visual approach critera, you don't need to conduct, or can discontinue the instrument approach. Obviously that critera is different by night; hence why you're wanting to conduct an instrument approach rather than circle from LSALT.
The speed limitations are there to keep you within the area surveyed when they build the approach, just because it's VMC, doesn't mean you can disregard the speed limits, because you obviously still can't see terrain. In terms of a straight-in approach, they're there to set you up for a stablised approach and reduce your workload close to the ground.
I never saw it as a grey area, nor ever heard about it from any other pilots. I'd love to hear if anyone's view differs from this; I'd be quite surprised.
The speed limitations are there to keep you within the area surveyed when they build the approach, just because it's VMC, doesn't mean you can disregard the speed limits, because you obviously still can't see terrain. In terms of a straight-in approach, they're there to set you up for a stablised approach and reduce your workload close to the ground.
I never saw it as a grey area, nor ever heard about it from any other pilots. I'd love to hear if anyone's view differs from this; I'd be quite surprised.
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I agree with tmpffisch re the speed.
Definition of IMC in the CAR is meteorological conditions other than those designated by VMC.
VMC makes no reference to anything besides visibility and cloud separation so I dare say what you experienced was still vmc at night.
at night you're effectively in IMC until inside the circling area
VMC makes no reference to anything besides visibility and cloud separation so I dare say what you experienced was still vmc at night.
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Agree with tmppfisch, if you're descending below LSALT or MSA you're either on a DGA, Vectored, Instrument Approach, Thirty miles by day VMC or Circling Area by night (or PAPI)
If you're on the DGA or Instrument Approach you need to comply with the speed limits for the category you're operating to. It's not possible to drop down a category, but you can go up one if the approach allows (accepting the higher minima, and higher initial and final speeds).
If you're not complying with the above (ie descending early, outside the circling area, or busting speeds on an approach), you'll potentially hit cumulogranite.
You as the pilot are also responsible for terrain clearance once you descend below MDA/Circling Height. Just because you descend at the normal point on downwind/base, or even continue from the straight in approach does not mean you have adequate terrain clearance.
If you're on the DGA or Instrument Approach you need to comply with the speed limits for the category you're operating to. It's not possible to drop down a category, but you can go up one if the approach allows (accepting the higher minima, and higher initial and final speeds).
If you're not complying with the above (ie descending early, outside the circling area, or busting speeds on an approach), you'll potentially hit cumulogranite.
You as the pilot are also responsible for terrain clearance once you descend below MDA/Circling Height. Just because you descend at the normal point on downwind/base, or even continue from the straight in approach does not mean you have adequate terrain clearance.
20 years ago, at least 
, the requirements for calculating the LSALT for Night VMC were different to those for IFR. (10 miles either side of track, instead of 12.5º+5 miles, from old memory). For a couple of regular destinations, I would fish out a WAC chart, and work out a night VMC LSALT, which was usually quite a bit lower than the IFR LSALT. If inbound and visual at night, I could then descend to that lower LSALT, and descend in the circuit once within the circling area.
, the requirements for calculating the LSALT for Night VMC were different to those for IFR. (10 miles either side of track, instead of 12.5º+5 miles, from old memory). For a couple of regular destinations, I would fish out a WAC chart, and work out a night VMC LSALT, which was usually quite a bit lower than the IFR LSALT. If inbound and visual at night, I could then descend to that lower LSALT, and descend in the circuit once within the circling area.
"need not commence or may discontinue the instrument approach procedure when:"
b. ByNight.AtanaltitudenotbelowtheLSALT/MSAfortheroute segment, the appropriate step of the DME or GPS Arrival Pro- cedure, or the MDA for the procedure being flown, the aircraft is established:
(1) clear of cloud;
(2) in sight of ground or water;
(3) with a flight visibility not less than 5,000M; and
(4) within the circling area or VAA - H, as applicable; or
(5) within 5NM (7NM for a runway equipped with an ILS) of
that aerodrome aligned with the runway centreline and established not below “on slope” on the T-VASIS or PAPI; or
(6) within 10NM (14NM for Runways 16L and 34L at Sydney) of that aerodrome, established not below the ILS glide path with less than full scale azimuth deflection.
Note: Reference to circling area in this section includes the circling area for the category of aircraft or a higher category where the limi- tations of the higher category are complied with.
So, if you are still using DGA steps, or in your example an RNAV with no PAPI, to descend, then you may not discontinue the approach until established in the circling area, so the speeds still apply.
If it were an ILS, however, and within the distance limitations, you can start the visual approach not below glide slope and as you have not commenced or have discontinued the speed restrictions do not apply.
Another example I can think of would be where approach may descend you by dme steps without actually giving you the approach. In this case you have never commenced any approach until hitting the circling area or established on the papi.
b. ByNight.AtanaltitudenotbelowtheLSALT/MSAfortheroute segment, the appropriate step of the DME or GPS Arrival Pro- cedure, or the MDA for the procedure being flown, the aircraft is established:
(1) clear of cloud;
(2) in sight of ground or water;
(3) with a flight visibility not less than 5,000M; and
(4) within the circling area or VAA - H, as applicable; or
(5) within 5NM (7NM for a runway equipped with an ILS) of
that aerodrome aligned with the runway centreline and established not below “on slope” on the T-VASIS or PAPI; or
(6) within 10NM (14NM for Runways 16L and 34L at Sydney) of that aerodrome, established not below the ILS glide path with less than full scale azimuth deflection.
Note: Reference to circling area in this section includes the circling area for the category of aircraft or a higher category where the limi- tations of the higher category are complied with.
So, if you are still using DGA steps, or in your example an RNAV with no PAPI, to descend, then you may not discontinue the approach until established in the circling area, so the speeds still apply.
If it were an ILS, however, and within the distance limitations, you can start the visual approach not below glide slope and as you have not commenced or have discontinued the speed restrictions do not apply.
Another example I can think of would be where approach may descend you by dme steps without actually giving you the approach. In this case you have never commenced any approach until hitting the circling area or established on the papi.
does this mean at night you're effectively in IMC
There are a lot of people (including some in positions that should know better) that don't fully understand the subtleties in the definitions of VMC, IMC, VFR and IFR.
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just because it's VMC, doesn't mean you can disregard the speed limits, because you obviously still can't see terrain
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Tee Emm, close. The circling area size is designed based from the max speed it's supposed to be flown, probably best to keep within it. I have seen somewhere that went into wind factors and rate of bank etc for these circuits, but can't remember where it was now...:
from a position within the circling area on the down-wind, base or final leg of the landing traffic pattern at an altitude not less than the MDA, can complete a continuous descent to the landing threshold using rates of descent and flight maneuvers which are normal for the aircraft type and, during this descent, maintains an obstacle clearance along the flight path not less than the minimum for the aircraft performance category until the aircraft is aligned with the landing runway
The circling area is calculated using the aircraft category speeds for circling (i.e. B @135kIAS) and assumes (for a 2000 feet elevation aerodrome)
1. A 25 kt wind through the turn
2. 20° angle of bank, or 3° per second, whichever is less.
It's in PANS-OPS. Note - go to some parts of the world and it will be different....
1. A 25 kt wind through the turn
2. 20° angle of bank, or 3° per second, whichever is less.
It's in PANS-OPS. Note - go to some parts of the world and it will be different....
Last edited by compressor stall; 12th Jun 2012 at 12:52.
You must absolutely abide by the speed restrictions whether you're in IMC or VMC. As has already been stated, if you track via an instrument approach at night you are doing an instrument approach until you meet the specified criteria for being able to do a visual approach and therefore, the approach speed restrictions apply. Whether you're in IMC or can see the aerodrome from 50 miles away is of no consequence.
This is poorly understood by many people, including quite a few training captains I've come across. At night, when someone says "Well we're visual, are you happy to keep the speed up?", they're showing a fundamental lack of understanding of the differences between day and night visual approaches. The confusion arises from the difference between VMC and being 'visual'. You're not visual at night until you meet the criteria, no matter what the weather is doing.
This is poorly understood by many people, including quite a few training captains I've come across. At night, when someone says "Well we're visual, are you happy to keep the speed up?", they're showing a fundamental lack of understanding of the differences between day and night visual approaches. The confusion arises from the difference between VMC and being 'visual'. You're not visual at night until you meet the criteria, no matter what the weather is doing.
However you could barrel along at 250 kts at the LSALT, then at 2.66/4.2 nm as appropriate to run, throw the anchors out and descend into the circling area at 135/180 kts.....
Now a slight digression, can you be IMC and see the aerodrome 50nm away?
Now a slight digression, can you be IMC and see the aerodrome 50nm away?
Last edited by compressor stall; 13th Jun 2012 at 08:55.
Now a slight digression, can you be IMC and see the aerodrome 50nm away?
Why not?? If you don't meet the VMC criteria, you are not in VMC, and it is a lot more than visibility. Just because you cab see 50nm doesn't mean you make the separation from cloud criteria to qualify as being in VMC conditions.
Which brings up the point, there has been much loose talk confusing weather conditions, IMC or VMC, and IFR and VFR.
At the risk of stating the bleeding obvious, but I will, a VFR aircraft must (should) maintain VMC.
For the purposes of a "visual approach" the criteria have already been cut and pasted in a previous post, that is not VMC. An IFR flight does not have to be in VMC to conduct a visual approach.
Also, make certain you understand that a visual approach is not the same thing as the visual segment (circling) if an instrument approach.
Tootle pip!!
Why not?? If you don't meet the VMC criteria, you are not in VMC, and it is a lot more than visibility. Just because you cab see 50nm doesn't mean you make the separation from cloud criteria to qualify as being in VMC conditions.
It's the lack of understanding of the IMC definition that something I notice frequently, hence my question. Many people think of IMC as in cloud only.If there is one Cu in the sky and you are cruising around it at 6000 feet but nice and close as we all love to do you are IMC, even though you can see 100nm.
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Thanks for all the thoughts - what Dragun was alluding to was what I had experienced and that's why I asked what I did. It's interesting making the transition from rote learning this all as "knowledge" as part of the CIR training then putting into practice in day to day IFR ops. Cheers
In the "real world" you need a "general safety rule", and that is that you can't commit the aircraft to IMC until you know what is providing your terrain clearance guarantee.
LSALT provides your terrain clearance en route.
The mnemonic "25, 30, VIRD" gives you your terrain clearance for your descent.
within 25 miles I can use the MSA, within 30 miles by day I can proceed visually, on VASI within 5/7 miles, on an Instrument approach, on Radar vectors, on a DME/GPS arrival.
In the real world, however, a lot of people forget about what is providing terrain clearance on their departure.
At a major airport, the SID gives you terrain clearance, at a standard 3.3% (unless specified otherwise on the chart). At, say 90 knots, that's a required vertical speed of 300 fpm.
At a typical bush aerodrome (say with an aid and approach) on a bad weather day with an IFR plan, many pilots take off into cloud (because they are "IFR") and climb out en route, not thinking about what is guaranteeing their terrain clearance up to the LSALT.
LSALT provides your terrain clearance en route.
The mnemonic "25, 30, VIRD" gives you your terrain clearance for your descent.
within 25 miles I can use the MSA, within 30 miles by day I can proceed visually, on VASI within 5/7 miles, on an Instrument approach, on Radar vectors, on a DME/GPS arrival.
In the real world, however, a lot of people forget about what is providing terrain clearance on their departure.
At a major airport, the SID gives you terrain clearance, at a standard 3.3% (unless specified otherwise on the chart). At, say 90 knots, that's a required vertical speed of 300 fpm.
At a typical bush aerodrome (say with an aid and approach) on a bad weather day with an IFR plan, many pilots take off into cloud (because they are "IFR") and climb out en route, not thinking about what is guaranteeing their terrain clearance up to the LSALT.
Last edited by Checkboard; 13th Jun 2012 at 13:33.
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In the real world, however, a lot of people forget about what is providing terrain clearance on their departure.
At a major airport, the SID gives you terrain clearance, at a standard 3.3% (unless specified otherwise on the chart). At, say 90 knots, that's a required vertical speed of 300 fpm.
At a typical bush aerodrome (say with an aid and approach) on a bad weather day with an IFR plan, many pilots take off into cloud (because they are "IFR") and climb out en route, not thinking about what is guaranteeing their terrain clearance up to the LSALT.
At a major airport, the SID gives you terrain clearance, at a standard 3.3% (unless specified otherwise on the chart). At, say 90 knots, that's a required vertical speed of 300 fpm.
At a typical bush aerodrome (say with an aid and approach) on a bad weather day with an IFR plan, many pilots take off into cloud (because they are "IFR") and climb out en route, not thinking about what is guaranteeing their terrain clearance up to the LSALT.
What about flying the reciprocal of an RNAV, or GPS/DME arrival? Simple solutions that give you a surveyed 3 degree clearance.
Indeed - or, for a more "terrain challenged" airport, what would you do if you were circling, and lost visual contact?
You begin to climb, and turn towards the runway (because you know there is no terrain between where you are circling and the runway), and pick up the missed approach procedure. (2.5% climb gradient as standard.)
So, for a take-off, you can get airborne turn back to the runway, don't enter cloud until above the circling minima, and then pick up the most useful missed approach up to the MSA/LSALT before then departing on track ...
You begin to climb, and turn towards the runway (because you know there is no terrain between where you are circling and the runway), and pick up the missed approach procedure. (2.5% climb gradient as standard.)
So, for a take-off, you can get airborne turn back to the runway, don't enter cloud until above the circling minima, and then pick up the most useful missed approach up to the MSA/LSALT before then departing on track ...