ZA737 / ZA757

Application
Precision Approach Path Indicator (PAPI)units provide two colour (red/white) approach path information from a wingbar arrangement. A standard wingbar comprises four units, but may consist of two units when an abbreviated system is required. If two wingbars are used, each is is fed from a separate series circuit using either one or two constant current regulators. Fully operational from 100% to 0.3% brilliancy (80% for normal daytime setting), giving typically 3000 hours of useful lamp life. Filament failure indication I the series circuit can be provided.

The ZA737 is a three lamp unit, the ZA757 is a two lamp unit. Both have identical 2' to 3' of arc transition performance. Three lamp units allow one lamp out per unit still leaving a fully operational wingbar.

Compliance with standards
ICAO: Annex 14 Fig 2.20
FAA: AC 150/5345-28D
CAA: CAP 168 Figure 6A/18NATO: STANAG 3316
BSI: BS3224 Part 1

Features

• Over a decade of ALSTOM experience with development taking place alongside research carried out by the Royal Aircraft Establishment at Bedford, UK.
• Acquisition range, normal day 19km with met visibility 7 7km. (see table)
• Easy maintenance, whilst in service position. Lamp change can be carried out by unskilled staff in good or poor weather conditions using lamp access hatches at the rear of the PAPI unit.
• No special tools or instruments required for servicing. Optical bench not required.
• Three leg mounting for ease of levelling and elevation setting with natural stability built in for high wind and jet efflux conditions.
• Constant frangible facilities, regardless of mounting height.
• Lenses protected from direct impingement of driving raid and splashing. No front window to keep clean.
• ICAO 30° wide beam to obtain full advantage of MLS and to provide visual aid to touchdown.
• Careful attention to circulating airflow minimises cold weather condensation effects on beam performance. Lens heaters included with lamp circuit to provide even dispersions of condensation.
• ICAO settings will allow curved approach with offset of up to 6° without amendment to unit. Approach angles of 1° to 12° can be catered for.
• Large lampholder heat sink eliminates reflector surface crazing from lamp heat.

Supply
Suitable for all normal series circuit systems of 6.6A, 8.33A, 12A, 16A or 20A. Can also be used on constant potential systems.

Installation
The mounting system which is further described in Publication AVD1 and AVD2B, consists of 3 x 1 m collapsible aluminium alloy legs (which can be cut to the appropriate length) and a folded down base unit ZM130 for ZA737 and ZM131 for ZA757.