14 CFR 91.169 — IFR Alternate Airport Requirements (the 1-2-3 Rule)

When does 14 CFR 91.169 require you to file an alternate airport?

You must file an alternate unless two conditions are simultaneously met at your destination, per 14 CFR 91.169(b): a standard or special instrument approach procedure must be published for that airport, and the forecast weather must show at least a 2,000-foot ceiling above airport elevation and at least 3 statute miles visibility for the period from 1 hour before to 1 hour after your estimated time of arrival. If either condition fails — no approach procedure exists, or the forecast dips below 2,000/3 during that window — you must list an alternate on your IFR flight plan.

This is the "1-2-3 rule": 1 hour before, 1 hour after, 2,000 feet ceiling, 3 sm visibility. Instrument candidates are expected to state all four numbers on demand. Note that the weather source used for this determination is a forecast product — typically a TAF — not a METAR, because you are planning ahead of departure.

What weather minimums must a filed alternate airport meet?

Once you determine that an alternate is required, 14 CFR 91.169(c) sets the planning minimums the alternate must be forecast to meet at your ETA. The standard is split by approach type:

If the alternate has both a precision and a nonprecision approach, the lower precision standard (600/2) applies. These are planning minimums only — they determine whether you can legally list the airport as your alternate at dispatch. If you actually divert and fly an approach there, you use the published approach procedure minimums for that specific approach, not 600/2 or 800/2.

What if no instrument approach procedure is published at the alternate?

An airport without any published instrument approach procedure may still qualify as your alternate under 14 CFR 91.169(c)(2). The requirement is that the ceiling and visibility at your ETA must allow you to descend from the MEA, approach the airport, and land under basic VFR. In practice, this means forecast conditions at that airport must support VFR flight — typically a ceiling above 1,000 feet AGL and visibility of at least 3 sm, though "basic VFR" is defined by the airspace class around that airport.

This provision is most relevant for rural alternates at non-towered fields that have no instrument approach in the National Airspace System. You are effectively planning to arrive in VMC, descend visually, and land. If the forecast doesn't support that, the airport cannot serve as your alternate.

What are non-standard alternate minimums and what does NA mean?

Some airports have non-standard alternate minimums that are higher than the 600/2 or 800/2 defaults. When non-standard minimums apply, they are published in the front section of the FAA terminal procedures booklet (the "Alternate Minimums" pages), identified by an inverted black triangle with an "A" on the approach chart. You must look those up and apply them instead of the standard values when selecting that airport as an alternate.

The notation NA (Not Authorized) appearing in the alternate minimums section means the airport or a specific procedure cannot be used as an alternate under instrument flight rules. NA is commonly listed when factors such as an unmonitored navigational aid, limited operating hours, or unreliable weather reporting make the airport unsuitable for alternate planning. If you see NA for an airport's procedures, you cannot legally file it as your alternate — period.

• Standard precision alternate minimums: 600 ft ceiling / 2 sm visibility (14 CFR 91.169(c)(1)(i))
• Standard nonprecision alternate minimums: 800 ft ceiling / 2 sm visibility (14 CFR 91.169(c)(1)(ii))
• Non-standard minimums: published in terminal procedures booklet with inverted-A symbol
• NA notation: airport or procedure not authorized for use as an alternate
• No-approach alternates: forecast must allow descent from MEA and landing under basic VFR

How does 91.169 connect to fuel planning under 91.167?

14 CFR 91.169 determines whether you must file an alternate and what weather minimums it must meet. Fuel planning is a separate but linked obligation governed by 14 CFR 91.167. Under 91.167(a), when an alternate is required, you must carry enough fuel to: (1) reach the destination, (2) fly from the destination to the alternate, and (3) then cruise for 45 additional minutes at normal speed. The two regulations work together — 91.169 tells you what alternate to pick, and 91.167 tells you how much fuel that alternate choice requires you to carry.

The link matters on checkrides: DPEs routinely ask candidates to walk through an IFR flight plan and explain both which airport qualifies as the alternate under 91.169 and how the fuel requirement changes if the weather forecast at the destination improves and an alternate is no longer required. Understanding the relationship between the two regulations — not just the individual rules — demonstrates the systems-level thinking the ACS expects. Arrival and approach minimums at the destination are governed separately by 14 CFR 91.175.

Frequently Asked Questions

Q: What is the 1-2-3 rule in 14 CFR 91.169?

The 1-2-3 rule describes the conditions under which an alternate airport is not required. Under 14 CFR 91.169(b), you do not need an alternate if the destination forecast shows at least a 2,000-foot ceiling and 3 sm visibility from 1 hour before to 1 hour after your ETA, and an instrument approach procedure exists at the destination.

Q: What are the standard alternate minimums for a precision approach?

For an alternate airport with a precision approach (ILS, GLS, or PAR), the standard planning minimums are a 600-foot ceiling and 2 statute miles visibility per 14 CFR 91.169(c)(1)(i). These are planning minimums — not the approach minimums you fly at the alternate.

Q: What are the standard alternate minimums for a nonprecision approach?

For an alternate with only a nonprecision approach (VOR, LOC, RNAV, NDB), the standard planning minimums are an 800-foot ceiling and 2 statute miles visibility per 14 CFR 91.169(c)(1)(ii). If the alternate has both precision and nonprecision approaches, apply the lower 600/2 standard.

Q: Can I use an airport with no instrument approach procedure as an alternate?

Yes. Under 14 CFR 91.169(c)(2), an airport without a published instrument approach may serve as an alternate if weather conditions at your ETA will allow descent from the MEA, approach, and landing under basic VFR — meaning a ceiling and visibility sufficient for VFR flight.

Q: What does the NA symbol on an approach chart mean for alternates?

The NA (Not Authorized for alternate) notation means that procedure cannot be used to qualify the airport as an alternate under standard criteria. Non-standard alternate minimums, when published, appear in the front of the approach procedure booklet with an inverted A symbol. You must apply those non-standard values instead of 600/2 or 800/2.

Q: Are 91.169 alternate minimums the same as the approach minimums I fly?

No. The 600/2 and 800/2 minimums in 91.169(c) are planning minimums used at dispatch to determine whether an airport qualifies as your filed alternate. When you actually fly an approach at the alternate, you use the published approach procedure minimums for that approach, governed by 14 CFR 91.175.

Q: Does 14 CFR 91.169 apply to Part 135 or airline operations?

14 CFR 91.169 applies to Part 91 operations. Part 135 and Part 121 operators are subject to their own, more restrictive alternate airport rules under 14 CFR Parts 135 and 121 respectively, which add fuel buffer requirements and operational specifications.

Q: If I file an alternate, how much fuel must I carry to it?

Fuel requirements are governed by 14 CFR 91.167, not 91.169. Under 91.167(a), you must carry enough fuel to reach the destination, fly from the destination to the alternate, then cruise for an additional 45 minutes at normal speed.

Sources

• 14 CFR 91.169 — IFR Flight Plan: Information Required (Cornell LII)
• 14 CFR 91.167 — Fuel Requirements for IFR Flight (Cornell LII)
• 14 CFR 91.175 — Takeoff and Landing Under IFR (Cornell LII)
• FAA Instrument Flying Handbook (FAA-H-8083-15B)
• FAA Instrument Procedures Handbook (FAA-H-8083-16B)

This article was researched from FAA primary sources (14 CFR Part 91 via Cornell LII, Instrument Flying Handbook, Instrument Procedures Handbook) and citing current regulatory text — drafted by MockDPE. Last updated: May 2026. If you spot an inaccuracy, email corrections@mockdpe.org.