In general, airlines will accept any person with reduced mobility (PRM) who can understand and carry out the safety instructions by themselves, and who doesn't interfere with the in-flight safety or the activities of the crew.
Otherwise, the passenger may need a companion and, on specific occasions, health personnel with the capacity to apply the care needed.

Travelling with a companion is mandatory if you need assistance to:

• Get to an emergency exit.

• Communicate in any way with the crew about safety matters.

• Unfasten and fasten your safety belt.

• Carry out basic physiological needs.

• Access the life jacket or oxygen mask and put them on.

Except in special cases, your companion must be at least 18 years old and in full possession of their faculties.