How fast do the Boeing 737-800 and Airbus A340-300 cruise?

For aviation and real-world flying, a Boeing 737-800 typically cruises at about Mach 0.785, roughly 450 knots true airspeed (835 km/h), while an Airbus A340-300 normally cruises near Mach 0.82, about 470 knots TAS (870 km/h). Actual speed varies with altitude, temperature, weight and airline operating policy.

Typical cruise-speed comparison

These figures are representative planning speeds rather than fixed values that every flight must maintain.

The TAS figures are rounded estimates for normal high-altitude cruise temperatures. Maximum operating Mach is a limit, not a normal cruise target; crews retain a margin for turbulence, manoeuvring and temporary speed changes.

Which aircraft cruises faster?

The Airbus A340-300 normally cruises about Mach 0.035 faster than the Boeing 737-800. At the same atmospheric temperature, that represents roughly 20 knots of true airspeed.

This does not produce a proportional reduction in total journey time. Winds, routing, ATC restrictions, climb and descent profiles have greater influence, particularly when comparing a short-haul 737 flight with an intercontinental A340 service.

Neither aircraft holds one immutable cruise speed. Its flight management system can calculate an economic target using factors such as:

• Cost index: a lower value generally favours fuel economy, while a higher value gives more weight to journey time.
• Aircraft weight and altitude: a heavily loaded aircraft may begin at a lower cruise level and step-climb after burning fuel.
• Turbulence or speed restrictions: crews may select a different Mach number instead of accepting the managed target.
• Operator procedures: airlines can use different performance assumptions and economic policies.

Why are airliner cruise speeds given in Mach?

Mach number is used because compressibility and high-altitude aerodynamic limits depend on speed relative to the local speed of sound. The same Mach number can represent a different TAS when air temperature changes.

At cruise altitude, either aircraft may indicate only the mid-200s in knots IAS while travelling through the air mass at approximately 450–470 knots TAS. Our explanation of how IAS, TAS and Mach are used during a flight covers that distinction in detail.

Why can the groundspeed be much higher or lower?

Groundspeed includes the effect of wind, whereas Mach and TAS describe movement through the surrounding air. In simplified terms, a 450-knot TAS with a 100-knot tailwind produces about 550 knots over the ground; the same headwind reduces it to roughly 350 knots.

A high groundspeed shown by a flight tracker or simulator therefore does not mean the aircraft is exceeding its Mach limit. Crosswinds complicate the calculation because only the relevant wind component changes progress along the route.

What cruise speed should I use in a flight simulator?

Use the aircraft's ECON or managed cruise mode when it is modelled properly; otherwise, Mach 0.785 for the 737-800 and Mach 0.82 for the A340-300 are sensible baseline targets.

1. Follow the climb profile. Use indicated airspeed until the aircraft or flight plan changes to Mach near the crossover altitude.
2. Select the cruise target. Enter Mach 0.79 for the 737-800 if the control accepts only hundredths, or Mach 0.82 for the A340-300.
3. Watch the operating limit. Stay below the Mach barber pole and leave extra margin in turbulence rather than forcing the published maximum.
4. Judge speed by Mach or TAS. Do not dial 450 or 470 into an IAS speed window, and do not chase a groundspeed altered by wind.

Aircraft modelling also matters. Our 737-800 package with representative Mach 0.79 performance data provides useful context, while the A340-300 package with performance and limitations material helps when checking that type in a simulator. Simplified add-ons may not reproduce the thrust, drag or managed-speed logic closely enough to hold the real aircraft's figures at every weight and altitude.