In a "bootstrap" cooling system, the charge air is first compressed in the cold air unit to:

1) Cabin air for modern aircraft is usually taken from:

2) Engine bleed air used for air conditioning and pressurization in turbo-jet aeroplanes is usually taken from the:

3) Environmental system: in the air refrigeration unit, the water separation unit is placed:

4) In a "bootstrap" cooling system, the charge air is first compressed in the cold air unit to:

5) In a bootstrap cooling system the supply air is first: