Does part 91 require meeting DP climb gradients single-engine or only with two engines? Does it change the situation if it you are filed IFR in VFR weather? What about ATC climb gradients? We fly a part 23 CE525B and Part 25 CE680.
One job, many moons ago, we researched this rather extensively.
We were flying part 25 airplanes under part 91.
Under part 25 BFL through second segment calculations were the only ones that had to be done with one engine inop.
Under the TERPS and under part 91 any initial visual climb with a ceiling/visibility is mandatory regardless of airplane type or which part you operate under. Other than that DP’s/ATC restrictions don’t differentiate between VMC, IMC or type airplane. ATC assumes you are in the clouds unless you tell them otherwise and request a VFR climb for instance.
In our opinion, and rather amazingly, part 91 operations can use two engine data for the DP. So you calculate second segment but at the same time you can legally use two engine data to the end of the DP. Perhaps not exactly safe departing Aspen or Vail but legal. (did you know that most jets cannot circle inside the valley at Vail without exceeding a 25 degree bank angle?) Next time you are in the simulator and have some time to kill ask the instructor to clear up the weather, do a V1 cut and try to circle back for a landing.
Using that we came up with company procedures that were, in our opinion, safe but not as restrictive as using single engine data especially if you look at places like Toluca with fairly stiff climb requirements to relatively high altitudes through the mountains.
In VFR conditions you can see and avoid obstacles so two engine climb gradients were used for DPs.
When the weather was marginal but good enough to return we did two calculations, one was two engine for the entire DP, the other was one engine to the minimum altitude to execute an approach back to the airport.
If the weather precluded a return then we calculated two engines on the route we were flying with a one engine calculation to a departure alternate. The alternate could be in the opposite direction with a much lower MEA.
We felt those were good, safe and legal ways to still get out of places like Toluca with more than 1 passenger and 30 minutes of fuel.
Hope that helps,
John in Saudi
Thanks for the reply. IFR in the mountains or with obstacles I would plan to meet the single engine climb to be safe (even though part 91 doesn’t legally required it). This question came up because at MCO some DP’s have a ATC climb of 600 per NM to 2800. The aircraft I fly can’t comply with that climb, single engine, in certain conditions. I am wondering of the legalities. DO I have to notify them? What if it is VFR on a IFR clearance?
I can’t say that I have heard of anybody telling ATC they can’t make a restriction in case of a future engine loss. If you can’t make it on 2 then yes, by all means tell them and get a different departure. I suspect most controllers would understand bad climbs after an engine loss and would do what they can to hold or reroute other traffic but a “just in case” request would fill up the frequency unnecessarily. An engine loss gives you priority, they would hold all nearby departures until you get squared away. As a guess most airplanes would have trouble with that restriction on a hot, heavy departure with one out.
VFR on an IFR clearance only matters if you tell them you are VFR and request a VFR climb or something like that. Depending on the facility you are dealing with they may not do anything different with you. Asking LAX clearance delivery for a VFR climb is meaningless, you are still going to have to fly the DP for enroute flow. Departing West Podunk with a climb restriction because of one TV antennae 6 miles away and using a VFR climb makes sense.
If it is an ATC restriction on a DP that more than likely means traffic to/from another airport also has a restriction to NOT be at 2800 at the same point. They can get out of your way after you lose an engine.