Legally Required Instruments:
Altimeter, Variometer, Envelope Temperature and Fuel Quantity Gauge
are legally required in most countries.
Swiss made high-tech balloon instruments with gondola mounted
infrared temperature sensor. Both ACT 5000 and ACT 8000 offer more special
functions than you would ever want, including memorisation of data for the
last 20 flights. The ACT 8000 also has a barograph function.
Blue Sky Avionics(formerly Ball Variometers):
Ball's M-55 is a combination altimeter/variometer with a remote
envelope temperature probe. The M-55 is not available for direct
purchase. Ball functions as an original equipment manufacturer (OEM)
for the M-55, which is then certified together with an individual
balloon by its manufacturer. In 2000, Ball also introduced the M-57,
a fully digital balloon instrument package that adds a GPS interface
and flight review and mapping functions when connected to a Windows
This table compares the technical data of various basic electronic
A few builders have designed their own electronic envelope temperature
Most balloonists and airshippers use handheld aviation radios to
communicate with their ground crew, other aircraft and air traffic control (ATC).
makes my favorite handheld transceiver, the A-3 (A-3E in Europe).
A transponder (actually, an encoding altimeter with a 2644 code
transponder) is an instrument which transmits your flight altitude to
a control tower's radar for routing and collision avoidance purposes.
Unless a special waiver has been obtained, a transponder is required
in certain controlled airspace (Classes A, B and C).
At least in the USA, most balloonists don't fly with transponders since
there is plenty of uncontrolled airspace. In Europe, transponders are
becoming more and more of necessity. Some light weight transponders are
available but most are fairly heavy. I don't know of any experimental hot
air balloons using a transponder.