# The Air Navigation Order 1995, Paragraph Part II: Scale L1


Column 1
Column 2
Column 3
Column 4
Vertical displacement of the flying machine in relation to flight levels
Capability of flying machine to descend (where relevant)
Period of supply of oxygen
Persons for whom oxygen is to be provided
A The whole period during which, after a failure to maintain a pressure greater than 700 millibars in the control compartment and in the compartments in which passengers are carried has occurred, the flying machine flies above flight level 100.
B The whole period during which, after a failure to maintain such pressure has occurred, the flying machine flies above flight level 150.
C The whole period during which, after a failure to maintain such pressure has occurred, the flying machine flies above flight level 100, but not above flight level 150.
X The flying machine is capable, at the time when a failure to maintain such pressure occurs, of descending in accordance with the emergency descent procedure specified in the relevant flight manual and without flying below the minimum altitudes for safe flight specified in the operations manual relating to the aircraft, to flight level 150 within 6 minutes, and of continuing at or below that flight level to its place of intended destination or any other place at which a safe landing can be made.
Y The flying machine is capable, at the time when a failure to maintain such pressure occurs, of descending in accordance with the emergency descent procedure specified in the relevant flight manual and without flying below the minimum altitudes for safe flight specified in the operations manual relating to the aircraft, to flight level 150 within 4 minutes, and of continuing at or below that flight level to its place of intended destination or any other place at which a safe landing can be made.
Above flight level 100
—
30 minutes or the period specified at A hereunder whichever is the greater
In addition to any passengers for whom oxygen is provided as specified below, all the crew
Above flight level 100 but not above flight level 300
{ Flying machine is either flying at or below flight level 150 or is capable of descending and continuing to destination as specified at X hereunder
30 minutes or the period specified at A hereunder whichever is the greater
10% of number of passengers
{ Flying machine is flying above flight level 150 and is not so capable
{ 10 minutes or the period specified at B hereunder whichever is greater
All passengers
{ and in addition
{ 30 minutes or the period specified at C hereunder whichever is the greater
10% of number of passengers
Above flight level 300 but not above flight level 350
{ Flying machine is capable of descending and continuing to destination as specified at Y hereunder
30 minutes or the period specified at A hereunder whichever is the greater
15% of number of passengers
{ Flying machine is not so capable
{10 minutes or the period specified at B hereunder whichever is the greater
All passengers
{ and in addition
{ 30 minutes or the period specified at C hereunder whichever is the greater
15% of number of passengers
Above flight level 350
—
{ 10 minutes or the period specified at B hereunder whichever is the greater
All pasengers
{ and in addition
{ 30 minutes or the period specified at C hereunder whichever is the greater
15% of number of passengers

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Source: https://www.legislation.gov.uk/uksi/1995/1038/schedule/4/paragraph/Partn2 (the official version)
Page: https://openlegislation.uk/air-navigation-order-1995/schedule-4/paragraph-Partn2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.