B737-700 crew departed without a legal alternate. The crew returned to their point of origin.

Attributes
ACN	602138
Time
Date	200312
Day	Sun
Place
Locale Reference	airport : mht.airport
State Reference	NH
Environment
Flight Conditions	IMC
Weather Elements	Snow
Light	Night
Aircraft 1
Controlling Facilities	tower : mht.tower
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	descent : approach landing : missed approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 270 flight time type : 12400
ASRS Report	602138
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 200 flight time total : 14000 flight time type : 3500
ASRS Report	602142
Events
Anomaly	inflight encounter : weather non adherence : company policies non adherence : far non adherence : published procedure
Independent Detector	other flight crewa other flight crewb other other : 3
Resolutory Action	controller : issued new clearance flight crew : diverted to another airport flight crew : landed as precaution other
Consequence	other
Supplementary
Problem Areas	Company Flight Crew Human Performance
Primary Problem	Company

Narrative:

Flight was dispatched inadvertently without a second alternate. Although runway 17 at mht has visibility limitations to 1/2 mi, the runway was OTS as per 'chart NOTAMS.' the forecast WX for our approximately arrival time was 'FM XA00 050 degrees 14 KTS gusting 22 KTS 3/4 SM -- sn broken overcast 005 tempo XA07 1/2 SM sn vv 003.' the taf at our approximately departure time for mht was '14 XU39Z, mon, 00XV 06011 1/2 SM sn VV005 tempo XV03 1/4 SM +sn VV002.' exemption rule applied because runway 17 ILS was OTS and this was not noticed in the chart NOTAMS. Also, the winds would have dictated using runway 6 (most likely). We diverted back and landed uneventfully. Discussions with my dispatcher revealed (after our flight) that we needed the second alternate.

Original NASA ASRS Text

Title: B737-700 CREW DEPARTED WITHOUT A LEGAL ALTERNATE. THE CREW RETURNED TO THEIR POINT OF ORIGIN.

Narrative: FLT WAS DISPATCHED INADVERTENTLY WITHOUT A SECOND ALTERNATE. ALTHOUGH RWY 17 AT MHT HAS VISIBILITY LIMITATIONS TO 1/2 MI, THE RWY WAS OTS AS PER 'CHART NOTAMS.' THE FORECAST WX FOR OUR APPROX ARR TIME WAS 'FM XA00 050 DEGS 14 KTS GUSTING 22 KTS 3/4 SM -- SN BROKEN OVCST 005 TEMPO XA07 1/2 SM SN VV 003.' THE TAF AT OUR APPROX DEP TIME FOR MHT WAS '14 XU39Z, MON, 00XV 06011 1/2 SM SN VV005 TEMPO XV03 1/4 SM +SN VV002.' EXEMPTION RULE APPLIED BECAUSE RWY 17 ILS WAS OTS AND THIS WAS NOT NOTICED IN THE CHART NOTAMS. ALSO, THE WINDS WOULD HAVE DICTATED USING RWY 6 (MOST LIKELY). WE DIVERTED BACK AND LANDED UNEVENTFULLY. DISCUSSIONS WITH MY DISPATCHER REVEALED (AFTER OUR FLT) THAT WE NEEDED THE SECOND ALTERNATE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.