Transform the way you fly
Canada Air Pilot · Operating Minima — Alternate

Alternate weather minima calculator

Work out the IFR alternate-aerodrome weather minima the way the Canada Air Pilot (CAP GEN) actually requires — the greater of the standard floor or the additive over your lowest usable approach — and check a forecast against it, including BECMG, TEMPO and PROB groups. Handles the sliding scale, aerodromes without a TAF, helicopters, and the GNSS restrictions.

Guidance only, based on the CAP GEN "Operating Minima – Alternate" tables. Not a dispatch tool — always verify against the current CAP GEN and your ops manual.

Aircraft
Aeroplane
Helicopter
Forecast available at the alternate
The standard tables assume a TAF. Aerodromes without a TAF have their own, higher requirements.
TAFAerodrome forecast
Aerodrome AdvisoryNo TAF
GFA onlyGraphic Area Forecast
Best usable approach(es) at the alternate
Use the lowest usable approach(es), considering NOTAMs and your aircraft's equipment.
Two+ precisionto separate runways
One precision / APV
Non-precision onlyIncluding LPV
No IFR approach
Height above touchdown of the lowest usable approach.
ft
The vis on that approach's minima line. Decimal or fraction (¾, 0.75, 1 1/2).
SM
The lowest IFR altitude from which you could complete a VFR approach and landing.
ft
Height above touchdown/aerodrome of the lowest usable approach at the alternate.
ft
Cumulonimbus (CB) in the GFA for the area?
No CB forecast
CB forecast
Forecast at your ETA (at the alternate)
The ceiling and visibility the forecast shows for your estimated arrival time.
No ceiling (FEW / SCT / SKC)? Enter 9999.
ft AGL
Decimal or fraction (3/4, 0.75, 1 1/2). Use 6 or P6 for P6SM.
SM
TAF change groups covering your ETA
Select every BECMG, TEMPO or PROB group whose period overlaps your ETA. In each group, leave a value blank if the group doesn't change it.
BECMGBecoming
TEMPOTemporary
PROBPROB30 / PROB40
BECMG group
Improving conditions count from the end of the BECMG period; deteriorating conditions count from the start. These conditions must not be below the alternate minima.
ft AGL
SM
ETA beforethe BECMG period
ETA duringthe BECMG period
ETA afterthe period ends
TEMPO group
TEMPO conditions must not be below the alternate minima.
ft AGL
SM
PROB group
PROB conditions must not be below the landing minima for the approach you'd fly (the HAT/HAA and visibility entered above).
ft AGL
SM
Is the usable approach satellite-based (GNSS / RNAV)?
No — conventional
Yes — GNSS/RNAV
Operator
General Aviation
Private (PORD) / Commercial (AOC)
RNP AR approach [RNAV (RNP)]?
No
Yes — RNP AR
Destination also satellite-based?
No
Yes
Fill in the fields above to calculate your alternate minima.

Book a consult with Cardinal →

Guidance based on the Canada Air Pilot (CAP GEN) "Operating Minima – Alternate" tables. It is not a dispatch or flight-planning system and does not replace the CAP GEN, the TC AIM, or your operations manual. Confirm every value against the current publications before you rely on it.

Cardinal Aviation · cardinalaviation.ca · Transform the way you fly.