Instrument PI: Philippe Nédélec, CNRS-Laboratoire d’Aerologie, Toulouse (nedp@aero.obs-mip.fr)
Package1 (also denoted P1) is the basic instrument of IAGOS. It is designed for the autonomous measurement of ozone and carbon monoxide and contains the data acquisition for the IAGOS Humidity Sensor (ICH) and the Backscatter Cloud Probe (BCP). It also records the position of the aircraft and provides data transmission for all IAGOS instruments connected with P1 via GSM.
P1 consists of the instrument unit and the pump box, which contains membrane pumps (PTFE coated) that compress the sample air from ambient pressure to cabin pressure. The ambient air is sampled via a pitot tube on the IAGOS inlet plate. The electronic interfaces of the BCP and the ICH are mounted on top of P1.
Ozone (O3) is measured by UV absorption at 253.7 nm, using the optical block of a Thermo Instruments Model 49 analyser. Ozone free air is generated by passing the ambient air through a scrubber. In flight calibration checks are made with a built-in ozone generator.
Time resolution: 4s
Precision: ±2%
Accuracy: ±2 ppb
Carbon monoxide (CO) is measured by infrared absorption using the gas filter correlation technique. In order to achieve larger sensitivity and time response, the absorption cell is operated at 2 bar and at a flow rate of 4 SLM. The IR detectors are peltier cooled for noise reduction. In-flight calibration includes regular measurements of CO-free air generated by passing the dried ambient air over a bed of Sofnocat.
Time resolution: 30s
Precision: ±5%
Accuracy: ±5 ppb
Operation
The instrument is designed for autonomous deployment over periods of up to 6 months. The actual deployment can be shorter if, e.g., malfunction or loss of sensitivity is encountered. The instrument operates fully automatically. Package 1 is started on ground when power is available in the aircraft, at least 2 hours before take-off. The data acquisition starts during take-off (ground speed > 50 m/s) and stops after landing (ground speed < 50 m/s). BCP is started 1 minute after take-off using the “landing gear up” and “engine 2 oil pressure” signals. It stops with the “langing gear down” signal before landing. The data are transmitted on ground using “the cargo door opened” signal via telecommunication (GSM) to the IAGOS data centre.
Before and after each deployment, the instrument is shipped to the laboratory for detailed quality assurance. Details of operating procedures, data analysis and quality assurance are described in the SOP.
Status
Package1 is installed in all IAGOS-CORE aircraft based on EASA STC obtained in 2011 for Airbus A340 and in 2014 for Airbus A330 aircraft.
Manufacturer
P1 was developed by Laboratoire d’Aerologie of CNRS and is manufactured and qualified to aeronautic certification procedure DO-160 by LMG Toulouse. Responsible Design Organisation (DO, EASA Part 21J): Sabena Technics BOD, Bordeaux.