Procedure for conducting Balloon Flights
All applications from scientific investigators for flight support by the NBF must be submitted to the Chairman, Balloon Board, at least one year in advance. (Application Form)
The Flight operations Department reviews the flight application to determine the type of services and equipment that will be required for rigging, electronic support and meteorological support. The Operations Group selects a balloon and estimates the cost of the balloon, the hydrogen gas, the parachute and other expendables for the proposed flight. The climatology data for the launch site is checked to determine whether the float duration required by the user can be obtained on the proposed balloon launching dates.
Flight Scheduling is based on the conditions necessary for a successful flight, such as seasonal requirements or flight duration. Generally, the balloon flights from NBF are scheduled between the 15th of October and the 15th of April. During the period May to September no launches are conducted due to pre-monsoon and monsoon weather conditions, which are not suitable for balloon launches.
After the approval for the flight is obtained from the Balloon Board, each experimenter is allotted a specific launch window of about two weeks duration by the Balloon Board based on the experiments projected by the user scientists. In case the flight is not conducted within the launch window for any reason, the flight is calledoff, and the experimenter has to reschedule his flight by seeking a fresh launch window.
The Balloons are launched only when all the following conditions are satisfied:
1. Surface wind should be less than or equal to 5 knots with a fairly steady direction during the time taken for launch operations (2 to 3 hours).
2. Cloud cover should not be more than 2-3 octas with no cumulonimbus (CB) clouds around the station.
3. The tropospheric westerly jet speed should be less than 35 meter/sec in the tropospheric region which is from 12 km to 20 km altitude.
4. The tropopause temperature should be warmer than -85°C.
5. Permission to launch the payload is obtained from the Airports Authority of India and the nearby Indian Air ForceStations for the intended launch window.
General information regarding flight operations has to be communicated to the Airports Authority of India (AAI), Government of India, at least one month in advance for getting their clearance. If an aircraft is used for balloon tracking, the approval of the AAI, Government of India, is also required. For operating on radio frequencies other than the ones that have been allotted to NBF, permission has to be obtained at least one month in advance from the Department of Communication, Government of India.
The AAI has imposed a restriction that the flight operations through ascent upto 15 Km and through descent below 15 Km altitude be confined to a limited area.
The NBF is surrounded by the Air Force flying areas in the northern sector and whenever the Air Force conducts night flying exercises, balloon launching may not be permitted. NOTAMS for balloon launch are accepted by the AAI, 72 hrs in advance, for three days at a time for the balloon launch. While a NOTAM is operative, additional notams are not permitted.
Balloon Flight Operational Corridor
Charges for NBF Services
Flight support services provided by the NBF to all scientists except those belonging to TIFR, is fully charged to the user's account. The flight support includes the cost of the balloon, the hydrogen gas, the parachute and rigging, the electronic interface, air-borne battery power supplies, flight and recovery facilities and services directly associated with flight support.
Memorandum of Understanding
Before flight support is approved for a foreign user, a Memorandum Of Understanding (MOU) must be concluded with the NBF. The MOU is an agreement negotiated between TIFR/ISRO and a foreign user's government or its designated representative agency. In general, an MOU states:
Specific flight support arrangements must still be made for individual flights. However, they must be in accord with the general agreement set forth in the MOU.
Even though Scientific ballooning is a safe experimental technique, there is always likelihood though extremely small of an accident either during launch or during the payload landing. In view of this, experimenters need to execute 'release of Liability and Indemnification Agreement'.
Handling Radio Active Materials
Radioactive sources of low energy X-rays and Gamma-rays (of several micro curies) have been used in the past with X-ray and gamma-ray astronomy payloads in order to check the calibration of proportional counters and scintillation counter set-ups. These have always been recovered along with the rest of the equipment. In view of the recent legal complexities, the use of radioactive sources in the payload is highly discouraged. If it is absolutely essential, then it is recommended to mount these sources securely and take precautionary measures to ensure that the local population does not lay its hands on such dangerous radioactive sources. It is also necessary that the users obtain the prior sanction of the Director, Health Physics Section of the Department of Atomic Energy, Government of India, for the use of radioactive sources with their equipment.
It is the responsibility of the individual scientists to ensure that the containment frames and the suspension systems designed and fabricated by them, are mechanically capable of withstanding the stress placed on them by the launch,the flight termination and the impact when the payload touches the ground.Several g's force is seen by the suspension lines during the initial free-fall and parachute deployment. Even the terminal velocity of the cargo parachutes used in the payload are ~5-7 m per sec. Suitable shock-absorbing crash-pads should be attached to the landing gear of the gondola to protect the payload components.