Part 91 IFR Takeoff Minimums

A colleague recently pointed me to an article (Takeoff in Dense Fog…) at boldmethod that argues that the IFR takeoff minimums listed on IFR charts apply, even to operations under Part 91, if you accept a clearance that includes a DP, ODP, or SID.

But in most cases, these IFR takeoff minimums do not apply to pilots flying under Part 91, EXCEPT if the pilot is assigned and accepts a published departure procedure that includes takeoff minimums.

boldmethod 12/30/2017

The article references 14 CFR § 91.175 Takeoff and landing under IFR, specifically the standard takeoff minimums listed in paragraph (f).

Paragraph (f)(1) of the regulation notes:

Unless otherwise authorized by the FAA, no pilot may takeoff from a civil airport under IFR unless the weather conditions at time of takeoff are at or above the weather minimums for IFR takeoff prescribed for that airport under part 97 of this chapter.

But the text that introduces paragraph (f) also specifically notes that:

This paragraph applies to persons operating an aircraft under part 121, 125, 129, or 135 of this chapter.

14 CFR § 91.175 Takeoff and landing under IFR

In other words, those minimums do not apply to operations under Part 91. As explained in the Landis Letter (1999) [PDF], a letter of legal interpretation from an attorney at the FAA:

…Section 91.175(f) further states that no pilot operating an aircraft under Parts 121, 125, 127, 129, or 135…may takeoff from a civil airport under IFR unless the weather conditions are at or above the weather minimum for IFR takeoff prescribed for the airport under Part 97.

My research has indicated that when section 91.116(c)–the predecessor to the current section 91.175–was first proposed for adoption in 1967, this issue arose and was addressed as follows: Several comments indicated that section 91.116(c) of the proposal could be interpreted to apply civil airport takeoff minimums to aircraft operators other than those operating under Part 121, 129, or 135. As this result was not intended [underline added], the language of the paragraph as adopted herein has been changed to make it clear that the minimums apply to aircraft operating under 121, 129, or 135 (32 FR 13909 Oct 6, 1967). Accordingly, I am constrained to agree with your analysis that a Part 91 flight can depart in weather conditions less than the minima prescribed for the SID.

Note that the letter above does not mention Part 91K, which applies to Fractional Ownership Operations. Those operations are subject to additional constraints described in the management specifications FAA approves for each operator.

And that legal interpretation does not address the wisdom of departing in LIFR–perhaps zero-zero conditions–even if a close reading of the regulations allows it when you’re operating under Part 91.

Many experts recommend that you depart IFR only if weather at the airport you’re leaving is at least at or above the minimums for an approach at that airport, should you need to return quickly after takeoff. Some folks go further and use the circle-to-land minimums as their baseline. Or they plan for a takeoff alternate, which also isn’t required for Part 91 operations, but is always prudent.

The Runway Environment in the RNAV Era

As of January 30, 2020, the FAA had published 4,048 RNAV (GPS) approaches with LPV (localizer performance with vertical guidance) minimums at 1,954 airports; 1,186 of those airports are not served by an ILS. The number of LPV-capable procedures is almost three times the 1,550 approaches with Category I ILS minimums, and 2,838 of the procedures with LPV minimums serve runways without an ILS,

For the latest totals, visit the Instrument Flight Procedures (IFP) Inventory Summary and Satellite Navigation — GPS/WAAS Approaches pages at the the FAA website.

FAA.gov

This capability to fly ILS-like procedures to thousands of runways at small-town and rural airports is a boon to IFR pilots. But you must carefully prepare to fly approaches to runways that don’t have the ground infrastructure associated with an ILS–most importantly an approach lighting system and accessories such centerline and touchdown zone lighting. And keep in mind that a non-ILS runway may not be as a long as you’re accustomed to–the minimum length for a runway served by an approach with LPV minimums is just 3200 ft. (more details here).

For more information about GPS-based approaches, see Required Navigation Performance (RNP) Approaches (APCH) .

FAA.gov

For example, here’s video of the final approach segment of the RNAV (GPS) RWY 16 procedure at Chehalis, WA (KCLS) during a night approach.

As the video shows, the runway can be hard to spot. It has REILs and a PAPI, but it’s in a dark area near a river. And you must remember to activate the lights by clicking the transmit button on the CTAF as you approach the airport. (The camera makes the scene look a little darker than it really was to human eyes–but you get the idea.)

Chehalis (KCLS) airport

That approach has an LPV decision altitude of 476 ft MSL (300 ft. AGL). The visibility requirement is 1 sm. That’s not much greater than the 200 ft DA and 1/2 sm visibility for a typical Category 1 ILS. But the environment is vastly different than that presented by an ILS runway with its bright lights and other big-city features.

Here’s an overview of the approach lighting systems associated with ILS procedures.

Instrument Procedures Handbook:
Figure 9-36. Precision and nonprecision ALS configuration.

Contrast the view at KCLS with the scene at Boeing Field (KBFI) in Seattle during the final stages of an ILS approach.

ILS RWY 14R at Boeing Field (KBFI)

Here’s an approach to runway 20 at Bremerton, WA (KPWT). KPWT is a non-towered airport, but runway 20 is served by an ILS approach, which includes an ALS.

KPWT

RNAV RWY 20 approach at KPWT

So, regardless of the type of approach you’re flying, make sure you review and prepare for the runway environment that you’ll encounter when you break out of the clouds and go visual. It’s especially important to know which of the visual cues described by 14 CFR §91.175 Takeoff and landing under IFR will be available.