Jet A vs Jet A-1: What Line Service Should Know
If you fuel jets in the U.S., you pump Jet A. Crews who fly internationally talk about Jet A-1, and some flight plans and fuel requests ask for it by name. The two are close relatives, and on most days the difference never comes up. When it does, it comes down to one number and one piece of paper.
Here's what actually differs, what doesn't, and what a line tech needs to get right.
Same Family, One Key Difference
Both grades are kerosene-type turbine fuels covered by the same specification, ASTM D1655. Jet A is the grade mainly used in the United States. Jet A-1 is the grade used across most of the rest of the world, where it's often also made to other specifications such as the UK's DEF STAN 91-091 or the joint industry checklist used at shared airport fuel systems.
The main difference is the freezing point, a measure of how cold the fuel can get before wax crystals form in it:
| Grade | Freezing point, max |
|---|---|
| Jet A | −40°C |
| Jet A-1 | −47°C |
Both grades share the same density range, 775 to 840 kg/m³ at 15°C, which works out to about 36.9 to 51.0 API gravity at 60°F.
Seven degrees Celsius doesn't sound like much. On a long flight at altitude, the fuel in the wing tanks can get cold enough for it to matter, so crews plan around the freezing point of the fuel they actually have.
The grades can also differ in additives. Jet A in the U.S. usually has no static dissipator additive (an additive that helps static charge drain out of the fuel), while Jet A-1 outside the U.S. normally contains one. The certificate or ticket for each batch tells you what's in it.
What Stays the Same on the Ramp
For day-to-day handling, the two grades are treated the same way:
- Quality checks. Appearance, water, and gravity or density checks follow your quality control manual, whichever grade is in the tank.
- Density and weight. The allowed density range is identical, so a gravity check tells you nothing about which grade you have. A fuel at 806.8 kg/m³ at 15°C is 43.79 API and 6.722 pounds per gallon either way.
- Misfueling risk. Both are jet fuel, and the dangerous mix-up is still jet fuel into a piston engine. The misfueling guide covers the checks that prevent it.
Why the Grade on the Paperwork Matters
Because the two grades look alike and share the same density range, the only way a crew knows what they received is what you tell them. If the ticket says Jet A-1 and the truck held Jet A, the crew may plan a cold flight around a freezing point the fuel doesn't have.
This got real attention in 2026. In May, the European Union Aviation Safety Agency issued Safety Information Bulletin 2026-04 on managing Jet A at airports that normally supply Jet A-1, after supply constraints on Jet A-1. One of the risks it describes is a delivery of Jet A on a ticket that says Jet A-1.
On the ramp, that comes down to a few habits:
- Write the grade on the ticket exactly as it appears on the delivery paperwork for the fuel in that truck or tank.
- If a crew asks for Jet A-1 and you supply Jet A, tell them before you fuel, not after. Whether the aircraft can use it is the operator's decision.
- Keep the batch paperwork where you can reach it, so you can answer questions about freezing point or additives with the actual certificate.
- Never relabel or describe fuel as a grade it wasn't delivered as, even when the two look the same.
Answering Crew Questions
International crews may ask for the density in kg/m³ at 15°C, the way Jet A-1 is usually certified, instead of API gravity. The numbers describe the same property: 43.79 API at 60°F is 806.8 kg/m³ at 15°C. If the density is going into an uplift check, give the temperature with it; the uplift check post explains why.
Where AvGrav Fits
AvGrav uses one fuel choice, Jet A / Jet A-1, with a typical range of 36 to 51 API at 60°F, which lines up with the shared density range of both grades. Correct a hydrometer reading to API at 60°F, or a density meter reading to 15°C, and every result shows API gravity, specific gravity, density at 15°C, and pounds per gallon together, so you can answer in whichever unit the crew uses.
If you're checking a delivery, enter the certificate's value in Ticket Density @ 15°C or Ticket API @ 60°F to see how your reading compares, against a tolerance you set from your own procedures. AvGrav is a reference tool for the math. It doesn't tell you which grade you have; the paperwork does.
Common Questions
What is the difference between Jet A and Jet A-1?
The main difference is the maximum freezing point: -40°C for Jet A and -47°C for Jet A-1. Both are kerosene-type jet fuels covered by ASTM D1655, with the same density range of 775 to 840 kg/m³ at 15°C.
Can an aircraft approved for Jet A-1 use Jet A?
That's the aircraft operator's call, based on the aircraft's approved fuels and the flight. Jet A's higher freezing point can matter on long, cold flights, which is why crews need to know which grade they received.
Do Jet A and Jet A-1 weigh the same?
They share the same density range, so the weight depends on the batch, not the grade. A fuel at 806.8 kg/m³ at 15°C weighs 6.722 pounds per gallon at 60°F whether it was sold as Jet A or Jet A-1.
AvGrav and this guide are reference and convenience tools, not certified measurement instruments or a substitute for a calibrated hydrometer, thermometer, or your organization's official procedures. Always follow your organization's quality control program and applicable regulations before accepting, rejecting, or releasing any fuel.