As for the piston twin turbine single argument. How many piston twins will maintain MOCA over the BC mountains when they are at gross weight, and don't give me book figures, they are bullSh%t. Exactly.
I see there needs to be some clarification inserted here. I was careful to use terms like "comparable" when I talk about twins and singles that are approved for IFR ops.
CAR 703 states:
Enroute Limitations
703.32 No person shall operate a multi-engined aircraft with passengers on board in IFR flight or in night VFR flight if the weight of the aircraft is greater than the weight that will allow the aircraft to maintain, with any engine inoperative, the MOCA of the route to be flown.
So we aren't talking about Twin Comanches or friggen Beech Travelaires.
The part that deals with SEIFR ops is:
Transport of Passengers in Single-engined Aircraft
703.22 (1) Subject to subsection (2), no air operator shall operate a single-engined aircraft with passengers on board in IFR flight or in night VFR flight.
(2) An air operator may operate a single-engined aircraft with passengers on board in IFR flight or in night VFR flight if the air operator
(a) is authorized to do so in its air operator certificate; and
(b) complies with the Commercial Air Service Standards.
The applicable standards says:
723.22 Transport of Passengers in Single-Engined Aeroplanes
The standard for transport of passengers in a single-engined aeroplane under IFR or VFR at night is:
(1) General
(a) only factory built, turbine-powered aeroplanes are permitted;
(b) the turbine-engine of the aeroplane type must have a proven Mean Time Between Failure (MTBF) of .01/1000 or less established over 100,000 hours in service; and
(c) pilot training in accordance with subsection 723.98(24).
(amended 2000/12/01; previous version)
(2) Aeroplane Equipment Requirements
(a) two attitude indicators which are powered separately and independently from each other;
(b) two independent power generating sources, either of which is capable of sustaining essential flight instruments and electrical equipment;
(c) an auto-ignition system, or alternatively, the Company Operations Manual must specify that continuous ignition must be selected "ON" for take-off, landing and flight in heavy precipitation;
(d) a chip detector system to warn the pilot of excessive ferrous material in the entire engine lubrication system in all regimes of flight;
(amended 2003/06/01; previous version)
(e) a radar altimeter;
(f) a manual throttle which bypasses the governing section of the fuel control unit and permits continued unrestricted operation of the engine in the event of a fuel control unit failure;
(g) sufficient supplemental oxygen to allow for an optimal glide profile during an engine out let-down from 25,000 feet until a cabin altitude of 13,000 feet;
(amended 2003/06/01; no previous version)
(h) an electronic means of rapidly determining and navigating to the nearest suitable aerodrome for an emergency landing; and
(amended 2003/06/01; no previous version)
(i) sufficient emergency electrical supply to power essential electrical systems, including auto pilot flight instruments and navigation systems, following engine failure throughout the entirety of a descent at optimal glide speed and configuration from the aeroplane’s operating level to mean sea level.
(amended 2003/06/01; no previous version)
So if you want to operate SEIFR, you need a radio altimeter whether you think it's a good idea or not.
So what is safer? And remember we are talking about commecial SEIFR ops that are only allowed in the air taxi category. Not a Cessna 150. Not your uncle's homebuilt. Is it safer to fly IFR ops in a piston twin capable of maintaining MOCA with one engine failed or is it safer to ride in a turbine single with a good engine TBO that will maintain another kind of MOCA (major obstruction collision altitude) when the fan fails?
In my opinion, no. But now that we are aware of the real issues and the relevant types of airplanes we can have a more meaningful discussion.