1000'-on-top IFR Ruling

[Spector42]

Hi everyone, first post on PPRuNe so here it goes...

I am working towards my instrument ticket and I've come across a few questions regarding IFR altitude assignment.

1) What, specifically, is 1000'-on-top, and when does it apply? I know the visibility and separation requirements but I don't understand the concept of the rule. :confused:

2) Can ATC vector you at altitudes below MOCA when radar identified. I seem to read conflicting rulings on this one. :ugh:

P.S - I'm from Canada!

[paco]

You've never heard of VFR OTT (over the top) in Canada? It should be on the PPL syllabus. It means you are flying above the top of the clouds, often full cloud cover.

Be aware, when flying OTT, that performance rules require you to land safely as well, so you should be careful in a single-engined aircraft.

Generally, when you are being radar vectored, ATC assume responsibility for terrain avoidance, but that is not an excuse for you to shrug off all responsibility! Check the CARs for specific stuff for Canada.

Talking of which, here is an extract from CARs In Plain English:

602.116 VFR Over-the-Top

You can do this in the cruise by day if you are at least 1,000 feet vertically from cloud, or have a vertical distance between layers of at least 5,000 feet, with at least 5 miles visibility and the weather at the destination is forecast for scattered cloud or clear and visibility of at least 5 miles with no precipitation, fog, thunderstorms or blowing snow from 1 hour before to 2 hours after ETA if you rely on a TAF. Otherwise, the after ETA time increases to 3 hrs. One point to note with OTT (and night) flight is that you must carry all relevant charts and publications for the proposed route and probable diversions, which essentially means you can't go without a map. Your choices are VNC, WAC or VTA. Normal VFR doesn't need charts, but you must be familiar with appropriate information for the trip.

[frac]

1) What, specifically, is 1000'-on-top, and when does it apply? I know the visibility and separation requirements but I don't understand the concept of the rule.


1000'-on-top exists in Canada but it is rarely used. It is an IFR clearance that allows you to select a VFR altitude for your route of flight. You are still under IFR but ATC no longer has to provide you with separation in most of the cases, only traffic information.

Suppose the following scenario: You are cruising IFR at 6000' in moderate low level turbulence and based on PIREPs and GFS, you estimate that 8000 or 10 000, would provide you with a smoother ride. Unfortunately, there is traffic on the same route, same direction 2000' above about the same speed, ATC cannot clear you to climb at 10 000' until proper separation is ensured. IF you are in VMC conditions, you can request a clearance to maintain 1,000 feet on top and climb to 8 500'. ATC will provide you with traffic information only and you will be able to climb to 8 500 or 10 500. If after half an hour, you estimate that you won't be able to maintain VMC, you ask ATC for a "hard" altitude and providing that separation can be assured, ATC may clear you for lets say 10 000'.

It is an extra tool in the toolbox but it is rarely used by pilots in Canada.

It is the canadian equivalent to the american VFR on Top IFR clearance

FAA: VFR ON TOP (http://www.faa.gov/air_traffic/publications/atpubs/atc/atc0703.html)

Transport Canada: 1000-ft-on-top IFR Flight (http://www.tc.gc.ca/eng/civilaviation/publications/tp14371-rac-8-0-2603.htm#8-8)


2) Can ATC vector you at altitudes below MOCA when radar identified. I seem to read conflicting rulings on this one.


If the MVA (minimum vectoring altitude) is below the published MOCA, ATC can vector you below the published MOCA.

[SouheilSinno]

As stated from CARs 8.7

"1 000-FT-ON-TOP" INSTRUMENT

FLIGHT RULES (IFR) FLIGHT

1 000-ft-on-top IFR flight may be conducted provided that


the flight is made at least 1 000 ft above all cloud, haze, smoke, or other formation;
the flight visibility above the formation is at least three miles;
the top of the formation is well defined;
the altitude appropriate to the direction of flight is maintained when cruising in level flight;
the "1 000-ft-on-top" flight has been authorized by the appropriate ATC unit; and
the aircraft will operate within Class B airspace at or below
12 500 ft ASL, Class C, D, or E airspace.

NOTE:

ATC does not apply separation to aircraft operating 1 000-ft-on-top except in the following conditions:

at night, separation is applied between an aircraft operating 1 000-ft-on-top and other aircraft if any of the aircraft are holding; and

2. between aircraft operating 1 000-ft-on-top and an aircraft operating on an altitude reservation approval.