Originally Posted by
Romasik
- I'm executing an unpublished missed approach procedure from low altutude with a sharp turn because the aircraft on takeoff roll is still on the runway.
- I'm reducing speed from M 0.85 to M 0.78 due to unexpected turbulence.
- I'm following TCAS RA.
These are all deviations from the acknowledged clearance. Shall I declare emergency with MAYDAY?
Those examples are quite irrelevant.
When You are on an IFR flight plan, You are required by the Regulations to comply with Your departure and route clearance. In case of an engine failure during takeoff you will most likely fly an EOSID or EFP which no-one is aware of, except yourself and your colleague. So, Fly-Navigate-Communicate. I do appreciate that some Operators do not specifically demand for a Mayday call during an engine failure on departure, however it is to be noted that flying "straight ahead 25NM - climb MSA" when taking-off in a busy (flat) terminal area when you were expected to start a left/right turn at DER as per your SID will very quickly attract more than a few questions from ATC which you don't really want at that stage, because you are busy dealing with more important matters.
Having an airplane in a state of "urgency" deviating from any clearance previously received and necessitating to have other traffic cleared from the surrounding is not exactly "routine" operations for ATCOS and other traffic around you.
Put into the equation also that primary ECAM actions related to engine failure do not ask you to switch immediately your TCAS mode to TA only (that will come later), hence you might very well find yourself at a height where RAs can start to be triggered (post inhibition below 1000 ft AGL) whilst flying on a single engine. You definitely do not want conflicting traffic around you, but hey you are crossing the departure/arrival axes of a couple of major international airports in the Paris TMA at 9AM LT during your "straight ahead MSA", why bother with a MAYDAY after all?
Regarding your "examples":
If an aircraft is still on the runway on takeoff roll and you are ordered/decide to go around you will fly your published missed approach procedure. ATC will give you an amended routing to avoid conflicting with the departing traffic that has been cleared for a departure that you are not aware of, so you have no idea where the guy will be turning next. The solution to visually separate yourself as you describe can work in non-radar and non-controlled areas, but you would have briefed it in advance as an additional threat.
The TCAS RA is a well documented procedure which you are required to follow and required to declare to ATC as TCAS-RA. All accounted for.
Reducing speed due to turbulence is a short-term action which does not bother anyone. If you need to maintain a significantly different MACH number for quite some time though, you will need A) to tell ATC and that's about it in radar environments or B) get a revised clearance in non-radar environments.
When we do stuff in the SIM that looks good in the SIM we are all happy. But this stuff must work in real life too because that's why we pay the big bucks to the ATOs for leasing the SIMs or the Manufacturers' to buy them.