I am publishing this because of some of the responses to my original comment: "
Everything you described after that is UNSAFE and ILLEGAL."
In regard ro Porepunkah departures, I sent the following to flight safety Australia 15 years ago. They did not publish it, because it showed up an ambiguity in the regulations.[note: this is a simplified version of the departure which I must use from my home base at the Porepunkah airfield in country Victoria]. Note also that this is analysed using the regulations as existed at the time. I don't believe they have materially changed in regard to this particular issue. I apologise for the single diagram not appearing, but you can look at the area on google maps to see the situation.
Regulation puzzler:
Scenario:
You wish to depart ifr from your airport at
A, which is at around 1000 feet altitude. To the south-west of A, there is a bloody great lump of granite (
Ob) which makes the Least Safe Altitude from A to
B 8000 feet. The least safe altitude from B to the airport at C then drops down to 4000 feet. These least safe altitudes are constructed according to the regulations, and the position of B has been chosen to be the closest point to A at which the en route LSA drops to 4000 feet. A is a small country strip, and no departure procedures have been promulgated for it.
The weather is IMC, and you establish a clear lateral separation from Ob - which is the only obstruction requiring an LSA greater than 4000 feet - during departure. Which of the following are valid departure procedures?:
- Climb at maximum climb rate to establish at 8000 feet before reaching B (you may need a rocket to do this), then descend to 4000 at B.
- Climb at a more achievable climb rate to pass through 4000 feet before reaching B, and then descend back down to 4000 feet at B.
- Climb on the AB leg to reach 4000 feet before B, then cruise at 4000 feet, or
- Climb at a lower climb rate to not reach 4000 before B, then cruise at 4000.
And, for an extra 10 points: Would your answer change if you were flying night VFR?
Answer:A, B and D are valid, C is not. And probably, a night VFR operation could adopt alternative (c).
Analysis: Probably to allow IFR departures from the myriad of smaller airports for which a formal IFR departure is not prescribed, the regulations allow (CAR188):
An aircraft may be flown along a route segment at a height less than (en-route lsa):
....
(b) during arrival or departure, if the aircraft is being flown:
(i) at a safe height above the terrain; and
(ii) in accordance with any instructions published in AIP; ...
Since no procedures have been promulgated specifically for this airport, (ii) does not apply, other than the statement (AIP en-route 4.3.2):
Note 4. The pilot in command is responsible for ensuring that :
a. terrain clearance is assured until reaching either en route LSALT or departure aerodrome MSA...
This allows pilots to depart in a way which is safe, but which involves less than the en-route lsa. Typically a pilot initially applies clear lateral separation (high hills to the south, climb out to the north).
The problem is back in CAR188, which defines “departure means the time during which an aircraft is climbing after take-off at a rate that is reasonable under the circumstances.”
Although most pilots would not like doing it, climbing at a lower rate of climb is OK, provided terrain clearance is ensured by the pilot using lateral separation. This is likely one of those crash and burn situations – if you crash, then you may be committing an offense as clearly you were not ensuring a reasonable under the circumstances climb rate. So while alternative (d) is OK, alternative (c) clearly is not, as it involves proceeding below the calculated LSA after cruise altitude is reached, and therefore is no longer (in the context of this regulation) part of the departure.
The situation with Night VFR is slightly different, as there is an allowance for step-down after a critical obstacle has been passed(CAAP 5.13-2(0)):
10.4.10 However, NVFR procedures allow for a step down descent based on a new LSALT when the aircraft's position has been positively determined by a visual fix as having passed a critical en-route obstacle.
In the context of “passed” I interpret this as “abeam to the aircraft's actual track”, though an expensive lawyer – and possibly even a reasonable man - may be equally able to be interpret it as “of no further threat to flight”. I did attempt to find reference to this NVFR step-down procedure higher up the regulatory chain and looked in all the usual places, but couldn't find it (I didn't look under the rock at the end of my garden however – never sure where all the caveats are located). NVFR is also slightly more ambiguous as the regulatory material place more emphasis on takeoff and landing, and less on departure.
So there you have it. I would suggest that most ifr pilots would probably adopt alternative (c) for their departure in this case, and yet it is the only one which is clearly invalid. Yes, the regulations are complex.
I would prefer to see departure defined along the lines of: “ departure means the time during which an aircraft is moving away from terrain in the vicinity of the airport, either by climbing or establishing lateral separation” however while this would allow (c), I wonder what the aforementioned expensive lawyer would make of “in the vicinity”?
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Professor Bob Pascoe retired from Charles Darwin University in 2007. His area of expertise includes design of aviation software, and he continues involvement in a couple of university research projects. Bob owns a PA32 aircraft and has an instrument rating.