The planned tax, unveiled by the German government in June as part of a multi-billion package of belt-tightening measures, would add at least €13 to shorter-haul flights within Europe, according to a draft law.
"We reject this tax completely," Peter Schneckenleitner, a spokesman for German flag carrier Lufthansa, Europe's biggest airline by passenger numbers, told news agency AFP. "For German passengers, it will definitely make travelling more expensive ... this will hit the German economy as a whole."
Citing independent studies, he estimated the introduction of the tax could lead to the loss of up to 10,000 jobs and cut passenger numbers by as much as five percent.
Joachim Hunold, head of Air Berlin, Germany's second-largest airline, also said passenger numbers would fall and that jobs would be lost.
When the plans were first revealed, the director general of the International Air Transport Association (IATA), Giovanni Bisignani, dismissed them as "the worst kind of short-sighted policy irresponsibility."
Wolfgang Mayrhuber, Lufthansa chief executive, also said at the time that the tax would be "an extra burden to slow us down."
The levy is set to run until a carbon-emissions trading scheme that has already been agreed comes into effect for air travel in 2012.
Berlin hopes it will fill government coffers with around €1 billion.