| PAPI |                             string
 |                                         Precision approach path indicator. |         
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                            | APAPI |                             string
 |                                         Abbreviated precision approach path indicator. |         
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                            | HAPI |                             string
 |                                         Helicopter approach path indicator. |         
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                            | VASIS |                             string
 |                                         Visual approach slope indicator system. |         
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                            | AVASIS |                             string
 |                                         Abbreviated visual approach slow indicator system. |         
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                            | TVASIS |                             string
 |                                         T-shaped VASIS |         
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                            | ATVASIS |                             string
 |                                         Abbreviated TVASIS |         
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                            | 3B_VASIS |                             string
 |                                         3 bar VASIS. |         
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                            | 3B_AVASIS |                             string
 |                                         3 bar AVASIS |         
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                            | 3B_ATVASIS |                             string
 |                                         3 bar ATVASIS. |         
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                            | PVASI |                             string
 |                                         Pulsating/steady burning visual approach slope indicator, normally a single light unit projecting two colours. |         
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                            | TRCV |                             string
 |                                         Tri-colour visual approach slope indicator, normally a single light unit projecting three colours. |         
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                            | PNI |                             string
 |                                         Alignment of elements system. |         
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                            | ILU |                             string
 |                                         A number of identical light units. |         
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                            | OLS |                             string
 |                                         Optical landing system for strip decks and aircraft carriers (sometimes available on ground air bases for training purposes). |         
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                            | LCVASI |                             string
 |                                         Low cost visual approach slope indicator: 3 sets of 4 white lights on 3 mounts usually on only one side of the runway. |         
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                            | OTHER |                             string
 |                                         Other type of visual approach slope indicator. |         
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