RELEASE AND RECORDER RECORD B4-19 
Whenever 100 percent relative humidity is exceeded by more 
than three ordinates, a level will be selected at the point 
where 100 percent was first exceeded and relative humidity 
above that point will be considered missing for the remainder 
of the flight. Likewise, when the indicated relative humidity 
is less than 10 percent by three ordinates or less the relative 
humidity will be regarded as 10 percent andused for all pur- 
poses as an accurate value. Whenever the indicated relative 
humidity is more than three ordinates less than 10 percent, 
a level will be selected at the point where the relative hu- 
midity was first indicated to be more than three ordinates less 
than 10 percent and relative humidity above that point will be 
considered missing for the remainder of the flight. 
7.5.3 Altitude. Those altitudes computed from doubtful or missing tem- 
perature data will be considered doubtful when the accumulated error 
in altitudes exceeds the limits in §B5-10.2. On the level where doubtful 
altitude begins, enter on the recorder record ''Begin doubtful altitude." 
7.6 Classification of Data Associated with either Malfunctioning of 
Equipment or Unusual Meteorological Conditions. Doubtful or missing 
temperature data are possible when: 
a. 
The instrument and/or ground equipment is malfunctioning 
and there are obvious evidences on the recorder record that 
erroneous data are recorded. 
The instrument and/or ground equipment is malfunctioning 
and there are no obvious evidences on the recorder record 
that erroneous data are recorded. If data for an observation 
are classified other than accurate and ifthe reason(s) are not 
apparent on the recorder record, notes to explain the reason(s) 
for this classification will be entered on WBAN-31A. 
There is an intermediate stratum of entirely missing or 
scattered temperature traces. 
7.7 Evidence of Malfunctioning. Some of the more obvious evidences 
of malfunctioning, the underlying causes, the general characteristics of 
these, and a guide for determining the possible error are: 
a. 
i= Ih (59 
Independent Temperature Shift. When the temperature fre- 
quency signal changes without a corresponding change in the 
low reference frequency signal, an abrupt shift will occur in 
the temperature trace without a change in the temperature 
before and after the shift. If the shiftis more than 1°C but not 
FMH#3 
