• NC Software is proud to announce the release of APDL - Airline Pilot Logbook version 10.0. Click here to view APDL on the Apple App store and install now.
  • Logbook Pro for Apple iOS version 8.1 is now available on the App Store. Major update including signature endorsements and dark/light theme support. Click here to install now.

IFR Take off Minimums - Part 91, MEL airplane?

satpak77

Marriott Platinum Member
Joined
Dec 2, 2003
Posts
3,015
Total Time
5000+
Ok, a bunch of us just got asked if twin engine must be able to meet, on one engine, the published IFR Take Off mins that exist at some airports, discussed here

http://myairplane.com/databases/approach/pdfs/SC5TO.PDF

Take a look at "Eagle Lake", min climb required is 420 FT per NM.

The question was "well, we know the plane can do it on two engines, but if your POH says on one engine, that it cannot do it, are you still legal to depart, under Part 91"

Every guy in the room said, no, cannot depart legally. We were told we were wrong, under Part 91, you can.

Comments? Either way, nobody could find this elaborated on in the FARs or we at least couldn't find it.

THanks
 

ackattacker

Client 9
Joined
Nov 14, 2004
Posts
2,125
Total Time
hah!
Under part 91 you can depart. Somebody else might chime in with more official and documented info but essentially part 91 (unlike 135 and 121) does not contain any aircraft performance restrictions. Your aircraft under 91 does not have to have ANY climb performance on one engine, period. Doesn't need accelerate-stop either. However the rules under which the aircraft itself is certified may or may not specify single-engine climb performance requirements. I would say that if your aircraft is certified using single-engine takeoff and climb performance data (commuter category and above) then you could be operating in violation of the operating limitations of the aircraft. However if it's a normal category aircraft then it is certified using both-engines operating and there's no need to consider engine-out performance.

My answer is not definitive though.
 
Last edited:

Singlecoil

I don't reMember
Joined
Jul 26, 2002
Posts
1,273
Total Time
8760
I think it depends more on which category the airplane in question was certified under, Part 23 or Part 25. I used to fly 402C's into and out of a 2300 foot strip under scheduled 135. There was no way we had accelerate stop distance or accelerate-go for that matter, but it was legal.

Some metroliners were certified under different regs, and even though they were essentially the same thing as the other ones, they were more limited because you had to have accelerate stop, whereas the other ones didn't. I can't remember which is more restrictive, 23 or 25.

So anyway, my answer is yes you can depart legally.
 
Last edited:

MauleSkinner

Well-known member
Joined
Sep 4, 2005
Posts
638
Total Time
10,000
Basically, the TERPS are all-engine criteria. Under 135 or 121, there's a legal requirement to have engine-out options that meet terrain separation requirements, but under Part 91 the requirement is "merely" a moral one.

Here's an excerpt from AC 120-91 that spells out the all-engine criteria pretty well, I think:
7. TERPS CRITERIA VERSUS ONE-ENGINE-INOPERATIVE REQUIREMENTS.
a. Standard Instrument Departures (SID) or Departure Procedures (DP) based on TERPS or ICAO Procedures for Air Navigation Services—Aircraft Operations (PANS-OPS) are based on normal (all engines operating) operations. Thus, one-engine-inoperative obstacle clearance requirements and the all-engines-operating TERPS requirements are independent, and one-engine-inoperative procedures do not need to meet TERPS requirements. Further, compliance with TERPS all-engines-operating climb gradient requirements does not necessarily assure that one-engine-inoperative obstacle clearance requirements are met. TERPS typically use specified all-engines-operating climb gradients to an altitude, rather than certificated one-engine-inoperative airplane performance.
As Singlecoil indicated, the certification basis for the airplane makes a difference in some areas, but again, it's a separate set of regulations from the TERPS-defined obstacle clearances.
 
Last edited:

avbug

Well-known member
Joined
Dec 14, 2001
Posts
7,602
Total Time
n/a
The question was "well, we know the plane can do it on two engines, but if your POH says on one engine, that it cannot do it, are you still legal to depart, under Part 91"

Every guy in the room said, no, cannot depart legally. We were told we were wrong, under Part 91, you can.

Every guy in the room was wrong.

Except the one that told you that under Part 91 you can legally go.

You can legally depart.

Think about it this way: in a single engine airplane you can depart under IFR if you can meet the climb gradient. Where are you going to go if you lose an engine then? Must you still plan on engine-out climb gradients to meet the requirements of the departure? Of course not.

Neither must you plan on single engine climb gradients to meet the requirements of the departure if you're in a multi engine airplane when operating under Part 91.

The issue of whether the airplane is a Part 23 or Part 25 category aircraft is largely irrelevant. Part 23 doesn't establish a minimum single engine climb gradient criteria that demands a positive climb, whereas Part 25 does...but even in a part 25 airplane operating under Part 91...one need not be required to make the climb gradient on one engine.

If operating under Part 121 or 135, it's a different matter.

As Singlecoil noted; whether you plan your operation to comply with the departure gradient with single-engine performance is a moral issue. It's no longer a matter of "can you," but "should you."

You should not. But you can.
 

Bank-n-Yank

Active member
Joined
Dec 25, 2002
Posts
41
Total Time
<6000
Part 23 doesn't establish a minimum single engine climb gradient criteria that demands a positive climb,

Unless the A/C is certified under Part 23 Commuter category.

Read: 23.57 [c], 3, i-iii
 
Joined
Feb 27, 2006
Posts
12
Total Time
2000
Simply put, Part 91 does not stipulate a requirement to adhear to climb requirements for departure. TERPS is definately "all-engines operating", but doesn't care how you do it... just that you do. For multi-engine 135/121 ops (depending on the nature and equippment), regs and/or company FOM/SOPs will most likely require 2nd segment calculations in where this would have to be considered. First and foremost, if it's VFR, the rules are "see and avoid", so as long as you can maintain a positive rate of climb, you're good to go. If you're mins are between VFR and 200-1, you would calculate a standard IFR climb of 3.3% to your MIA (minimum IFR altitude) which could be the MSA, MORA, MEA, etc. depending on routing and so forth. If you have mins below 200-1, you would compute a 420'/NM climb to 500 AGL. From there, compute a 3.3% to your MIA. The only FAA documents and FAR/AIM info published about takeoff climb, SIDs and obstacle DPs, etc can be found in:

91.129 (g)
91.130
91.131
91.515
135.379

Hope this helps yo.

Order 8260.3B - US Standards for Terminal Instrument Procedures (TERPS)
Order 8260.19C - Flight Procedures and Airspace
Order 8900.1 - Flight Standards Information Management Systems (FSIMS)
Aim, Chapter 5
 

matthewjohn

Well-known member
Joined
Jan 18, 2006
Posts
61
Total Time
8500
Everyone has heard that pt. 91 can take off zero zero. (if your stupid enough to do that). My question is: Are the visibility requirements from the TERPS (published on the charts) for the specific airport/ runway "regulatory"? (ie.. if it says you need a 1/4mi, 1000RVR etc.., do you have to have that 1/4 mile, 1000 RVR etc.. since that data came from the TERPS)
 
Joined
Feb 27, 2006
Posts
12
Total Time
2000
Under part 91 you are not required to follow any of the takeoff visibility/RVR minimums on the back of the chart. You can takeoff 0/0 regardless of the rvr or vis. The RVR and VIS numbers are posted on the back of the plate for 135 and 121 operations. If you are flying 121 or 135 you are held to the standard t/o mins. of 1 mile vis for 2 or less engines or 1/2 mile vis for 3 or more engine airplanes if nothing is posted on the back of the plate. If the back of the plate states a a rvr or vis. requirement, then you are held to that standard as long as you can meet the climb criteria and have the required the ground equip (lights, markings, etc.). If you cannot meet the climb criteria, than you have to reference the other box.
 

ackattacker

Client 9
Joined
Nov 14, 2004
Posts
2,125
Total Time
hah!
Under part 91 you are not required to follow any of the takeoff visibility/RVR minimums on the back of the chart. You can takeoff 0/0 regardless of the rvr or vis. The RVR and VIS numbers are posted on the back of the plate for 135 and 121 operations. If you are flying 121 or 135 you are held to the standard t/o mins. of 1 mile vis for 2 or less engines or 1/2 mile vis for 3 or more engine airplanes if nothing is posted on the back of the plate. If the back of the plate states a a rvr or vis. requirement, then you are held to that standard as long as you can meet the climb criteria and have the required the ground equip (lights, markings, etc.). If you cannot meet the climb criteria, than you have to reference the other box.

Except that every single 135 or 121 operator I have ever seen uses lower than standard takeoff mins as specified in their operations specifications.

I don't know who uses standard takeoff mins. Nobody as far as I can tell.
 
Joined
Feb 27, 2006
Posts
12
Total Time
2000
Except that every single 135 or 121 operator I have ever seen uses lower than standard takeoff mins as specified in their operations specifications.

I don't know who uses standard takeoff mins. Nobody as far as I can tell.

I believe I referenced that in the last part of my post "If the back of the plate states a a rvr or vis. requirement, then you are held to that standard as long as you can meet the climb criteria and have the required the ground equip (lights, markings, etc.). If you cannot meet the climb criteria, than you have to reference the other box."

My intention was to avoid referencing company ops specs. Didn't want to muddy up a confusing topic. But obviously if a company has approval to do something in their ops specs, than the far's become secondary to that. Without special approval, one can never take off with mins lower than what is on the back of the plate.
 
Top