Cruise altitude, oxygen?

[robains]

Great job with the evolution of this 310R. This is my twin piston "goto" aircraft for GA, it's absolutely the best GA piston twin I have in my fleet. The addition of TrueGlass and RealLight along with other system emulation is fantastic (external lighting still leaves room for improvement but I can use my blind eye).

I'm a little confused on "cruise" altitude ... as I understand it "this 310R" is not pressurized but is equipped with oxygen (76.6 cubic foot system). I'm planning on a long distance flight pushing fuel envelope (810nm) so I'm looking to cruise at 16000 ft around 150-160 Kts as the reference charts seem to indicate that's the best altitude for fuel economy.

I've never flown a GA above 10,000 ft, but I've had no problems skiing at 13,000 ft ... so I'm assuming the oxygen usage at 16,000 ft would be on an "as needed" basis and not a constant flow. However, I'm unable to find any oxygen system in this 310R, page 51 of the User Guide pdf it references using the oxygen system (Cruise step 9) "Oxygen Flow Indicator – Check Flow (Indicator Toward Mask Indicates Proper Flow)." So I'm assuming this option is not simulated, so restrict cruise to 10,000 ft?

Cheers, Rob.

[Stew]

I'm pretty sure the oxygen option is *not* modeled. That being said I've flown at 15,000 ft. with no problems--I forget what the cruising speed was, but I suspect you can manage your long distance trip at 15,000 with no problems, or if you choose, 16,000.

Let us know how it sorts out.

Cheers!

Stew

[Krazycolin]

Not simulated

[robains]

Thanks for responses, I'm at 10000 and "I think" I'll have enough fuel, leaned out to max but have a moderate head/side wind ... was in the clouds for most of departure route out of HTKJ (picked up some researchers from Kilimanjaro) but has calmed down now over Indian Ocean/Mozambique Channel heading to FMCZ (Dzaoudiz, Mayotte). Glad the Aux tanks were simulated

Cheers, Rob.

[raymie1028]

I believe A2A Simulations has a gradual "blackout" experience programmed into their aircraft once you start flying above 10K feet w\o oxygen--after a period of time flying at this altitude or above, the screen starts to darken and eventually will blackout. It has been too many years since I have read FAA regs. regarding oxygen requirements in non-pressurized GA aircraft and at what altitude passengers and pilot must be using oxygen.

[robains]

Found info on FAA web site ... MCAR Part 7

7.9.1.13 OXYGEN STORAGE AND DISPENSING APPARATUS

(a) [AAC] All aircraft intended to be operated at altitudes requiring the use of supplemental oxygen shall be equipped with adequate oxygen storage and dispensing apparatus.
(b) [AAC] The oxygen apparatus, the minimum rate of oxygen flow, and the supply of oxygen shall meet applicable airworthiness standards for type certification in the transport category as specified by the Authority.
(c) [AAC] No person may operate an aircraft at altitudes above 10,000 feet unless it is equipped with oxygen masks, located so as to be within the immediate reach of flightcrew members while at their assigned duty station.
(d) [AAC] No person may operate a pressurised aeroplane at altitudes above 25,000 feet unless:
(1) Flightcrew member oxygen masks are available at the flight duty station and are of a quick donning type;
(2) Sufficient spare outlets and masks and/or sufficient portable oxygen units with masks are distributed evenly throughout the cabin to ensure immediate availability of oxygen to each required cabin crew member regardless of his location at the time of cabin pressurisation failure
(e) [AAC] An oxygen-dispensing unit connected to oxygen supply terminals is installed so as to be immediately available to each occupant, wherever seated. The total number of dispensing units and outlets shall exceed the number of seats by at least 10%. The extra units are to be evenly distributed throughout the cabin.
(f) [AAC] The amount of supplemental oxygen for sustenance required for a particular operation shall be determined on the basis of flight altitudes and flight duration, consistent with the operating procedures established for each operation in the Operations Manual and with the routes to be flown, and with the emergency procedures specified in the Operations Manual.
(g) [AAC] The process to determine the amount of supplemental oxygen needed for non-pressurised and pressurised aircraft is contained in IS: 7.9.1.13.

I would imagine the health of the individual (age etc.) would be a determining factor in what altitude they can operate at safely. But regs say no more than 10,000 ft ... fortunately for me I completed the flight without incident at 10,000 FT with plenty of fuel remaining with Aux and Main I think I had about 26 Gallons left ... about 810nm left on full tanks ... I think I could do 1000nm but with no reserve. Island hoping so it's either make it or crash into the ocean.

It was a great flight, landing was a little hard (within limits) but without effective landing lights at night (hint hint Colin) I had no visual runway reference and flared early.

Cheers, Rob.

[Stew]

I will be sure to put on my oxygen mask the next time I fly above 10,000 ft.

[robains]

Haha ... you mean you haven't been doing that? I've got one that drops from my sim room ceiling ... and my old race car's fire system nozzles directed at my PCs.

Cheers, Rob.

[tttocs]

Rob, for your use flying the 310 as a private pilot the relevant regulation is actually in part 91 as below:

§ 91.211 Supplemental oxygen.

(a)General. No person may operate a civil aircraft of U.S. registry -

(1) At cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen for that part of the flight at those altitudes that is of more than 30 minutes duration;

(2) At cabin pressure altitudes above 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen during the entire flight time at those altitudes; and

(3) At cabin pressure altitudes above 15,000 feet (MSL) unless each occupant of the aircraft is provided with supplemental oxygen.

Living and flying in the Rocky Mountain west, I regularly flew my Turbo Arrow up to 14,000' for short periods of time (less than 30 minutes) when clearing ranges for extra safety margins without supplemental oxygen. Flying up to 12,500' was done routinely. Of course, as both I and my family lived at elevation and were physically active, it was both legal and safe. Had I lived at lower elevations, I might have been more cautious.

For the non-turboed 310, 12,500 is a not-unreasonable limitation for extended cruise.

Scott

[robains]

Hi Scott,

Excellent, thank you for correction.

I seem to recall reading (not sure where) the 310R takes approximately 4% more fuel to reach 16,000, but on a long range cruise with safety margins one should save 8% fuel so net gain of 4%.

For early part of this flight it would have been nice to be above the cloud layer, but given my course that would have been 17,500 ... cloud layer ended around 16,000. I think the service ceiling is 19750 ft?

Guess I'll just have to wait for the oxygen system add-on

Cheers, Rob.

[fppilot]

I'm planning on a long distance flight pushing fuel envelope (810nm) so I'm looking to cruise at 16000 ft around 150-160 Kts as the reference charts seem to indicate that's the best altitude for fuel economy.
cheers, Rob.

Are you using an add-on GPS? I would be interested in your experience with a long flight, say two-and-a-half hours of more. Particularly if the autopilot and GPS keep you true on your GPS-programmed course throughout your cruise.

Frank

[robains]

Hi Frank,

I'm using the F1 GTN 750/650 with MV WX Radar linked to NAV1. The flight duration was just a little over 5 hours ... can confirm exact duration tonight (in the office right now). I made a video for much of it and will post abbreviated version later this week.

No problem holding course, there was a moderate cross/headwind so was crabbing (is that a word?) along but still on course. I was a little concerned early in the flight as there was some Turbulence and I was worried the AP might turn off. I went out for lunch for a couple of hours, wife stayed home and checked the course track on my other PC (running LittleNavMap) ... told her to go hit P on my FS PC if she happened to see my aircraft stray off course. Fortunately she didn't and stayed on course all the way to approach and I took over around 2500 ft.

Speed did increase a little, but consistent with specs. My next flight will be continuation from FMCZ to FSIA (Seychelles) 770 nm or so ... the flight that will be the most challenging will be from FSIA to VRMG (Gan/Maldives) about 1060 nm ... winds are probably going to be critical in this leg (will try for 11,500 alt).

Cheers, Rob.

[fppilot]

Hi Frank,

I'm using the F1 GTN 750/650 with MV WX Radar linked to NAV1. The flight duration was just a little over 5 hours ... can confirm exact duration tonight (in the office right now). I made a video for much of it and will post abbreviated version later this week.

No problem holding course, there was a moderate cross/headwind so was crabbing (is that a word?) along but still on course. I was a little concerned early in the flight as there was some Turbulence and I was worried the AP might turn off. I went out for lunch for a couple of hours, wife stayed home and checked the course track on my other PC (running LittleNavMap) ... told her to go hit P on my FS PC if she happened to see my aircraft stray off course. Fortunately she didn't and stayed on course all the way to approach and I took over around 2500 ft.

Speed did increase a little, but consistent with specs. My next flight will be continuation from FMCZ to FSIA (Seychelles) 770 nm or so ... the flight that will be the most challenging will be from FSIA to VRMG (Gan/Maldives) about 1060 nm ... winds are probably going to be critical in this leg (will try for 11,500 alt).

Cheers, Rob.

Thanks for that Rob,
I have on three occasions strayed off course after about two hours on autopilot using a dual GPS configuration of an RXP 530 and RXP 430, both v2. The best attention I paid to it was during a flight from Alabama to Indiana with a strong headwind. I was away from the yoke as the plane should have made a turn at BNA (Nashville, TN). The plane had been following the flight plan accurately until that waypoint. When I noticed the off-course condition I confirmed the GPS was set to GPS, the AP was clearly still on NAV. The magenta line on the GPS showed the flight plan course, and the flight plan listing showed the magenta bracket accurately indicating the active flight plan leg. But I was off course as if I had been on the heading bug at BNA. I was not! I selected to go D-> to my next waypoint and flew the remainder of the flight to Indianapolis without fault.

The previous two instances were both during a long flight from Indianapolis to Denver. Just like the Nashville incident, the AP/GPS strayed off course when it should have made a turn at MCI, then again when in the Denver airspace at FQF. I PM'd Bill about that flight. Had not had it happen again until the Ala to Ind flight, but I had not in the interim flown a flight of more than two hours.

BTW, with the tip tanks, a light payload, full load of fuel, and good power management, this model can significantly exceed 900 nm. The flight from Indianapolis to Denver Rocky Mountain (KBJC) was right at 900 NM and I had a very strong headwind, and was off course for a while.

[tttocs]

Frank, I'm using the F1 650/750 plus wx radar combo with RXP units subbed in for the F1's and I've never seen the issue you've had to date - or at least not since my early teething problems when almost everyone was having issues.

My flights are generally in the 2+ hour range. In fact, on Sunday flying out of KTNP (real-time, RW wx with ASP4) up to Monterrey I was pretty impressed with how well the AP held considering the level of turbulence I was flying in until well NW of Palmdale.

Were any of your turns > 90d?

Scott

[Stew]

... with MV WX Radar linked to NAV1.

Rob, I'm curious about this. What do you mean the WX Radar is linked to NAV1?

Stew