24 Hour Clock – Time conversion Training

Attention: You can find time zones for the United States in the white pages of your phone book.

Most airlines use the 24-hour clock system when telling time. They use this system when assigning trip departures, check-in times and other forms of time designation. The 24-hour clock alleviates communication problems and is more convenient.

Typically, people tell time using a 12-hour clock (the numbers 1 through 12), and adding “a.m.” or “p.m.” to indicate morning or afternoon. Using the 24-hour clock system, you count each hour from O to 24 (because there are 24 hours in a day). When you reach 12 o’clock noon, you continue to count from 12 to 13 (1300 is 1:00 p.m., 1400 is 2:00 p.m., 1500 is 3:00 p.m., etc.) around the clock, until you reach 2400 or midnight.

At 2400, you start again from the beginning-0000 (which is also considered midnight) to 0001 (one minute after midnight) to 0002, 0003, 0004…0059, 0100 (which is 1:00 a.m.), 0101,0102, 0103, 0159, 0200, etc.

The following breaks down “a.m.” and “p.m.” hours.

0001 to 1159 = a.m. hours 1200 = noon

1201 to 2359 = p.m. hours 2400/0000 = midnight

When reading the 24-hour clock: 1000 is “ten hundred,” 0540 is “five forty,” 0030 is “zero thirty” and 1945 is “nineteen fourty-five.”

When using the 24-hour clock system it is not necessary to place colons between hours and minutes, or use the a.m. or p.m. designators. For example:

12-Hour Clock 24-Hour Clock
3:00 a.m. 0300
3:00 p.m. 1500
6:15 p.m. 1815
12:01 a.m. 0001
US./Canada Time Zones

The United States and Canada lie within eight standard time zones. Each of these zones uses a time one hour different from its neighboring zone. The hours are earlier to the west of each zone and later to the east.

The following is a list of time zones:

AST Atlantic Standard Time PST Pacific Standard Time
EST Eastern Standard Time YST Yukon Standard Time
CST Central Standard Time AST* Alaska Standard Time
MST Mountain Standard Time HST* Hawaiian Standard Time
*Alaska Standard (AST and Hawaiian Standard (HST) are two hours apart during Daylight Savings time. Because Hawaii does not observe Daylight Savings, AST and HST become one hour apart during Standard Time.

These zones extend through the Bahamas, Bermuda, Canada, Caribbean Islands, Mexico and the United States. Canada also has Newfoundland Standard Time (NST). Daylight savings time is standard time moved forward one how to provide an additional daylight hour in the evening. Example: 8:00 p.m. CST becomes 9:00 p.m. CDT. Daylight savings time extends from the beginning of April through the end of October. Conversion dates, standard to daylight and daylight to standard, are used by airlines for inaugurating summer and winter flight schedules.

Universal Time Coordinated (UTC) and the International Date Line

When people express time, they generally speak in terms of local time. International airlines deal with many time zones, and communication of time can be difficult. To eliminate confusion, a common time measurement was established; the Universal Time Coordinated or UTC (previously known as Greenwich Mean Time or GMT).

Imagine the world as a circle. A cycle has 360 degrees. There are 24 time zones throughout the world with each time zone consisting of 15 degrees. Twenty-four time zones multiplied by 15 degrees for each time zone equals 360 degrees, the Earth. Each country within a time zone adopts standard time convenient to that country. When one travels east of Greenwich, England (or from anywhere in that longitudinal zone) each zone entered to the east is an increase of one hour to UTC. Similarly, each time zone entered to the west of Greenwich, England, is a decrease of one hour to UTC. Airlines that fly internationally use UTC to standardize time for worldwide operation. UTC is used in the flight deck and will be the times you record in your flight logbook and payroll sheets. UTC is recorded as a 24-hour clock. International schedules are printed in local time, but preceding each city or airport is that vocation’s hour plus or minus from UTC. Another demarcation is the International Date Line IDL) which generally follows 180 degrees longitude approximately halfway between Honolulu and Tokyo, Japan. Countries west of this line are a day ahead of those east of the line.

Flying over the International Date Line:

Monday Monday Sunday
0002 UTC 0102 UTC 0202 UTC
A day is lost A day is gained
Flying a day west is lost time, but some is regained as time zones are crossed. Flying a day east is gained time, but some is lost as time zones are crossed.

*The International Route map and corresponding time zone table is available in the World Traveler magazine.

The world time zones are not required to complete these exercises.

24-Hour Clock Exercises

Exercise #1

Convert the following to 24-hour time.

10:00 p.m. _____________ 5:15 a.m. _____________
3:15 a.m. _____________ 3:40 p.m. _____________
noon _____________ 1:55 a.m. _____________
5:30 p.m. _____________ 6:30 a.m. _____________
10:10 a.m. _____________ 9:17 p.m. _____________
7:55 p.m. _____________ 8:00 p.m. _____________
2:45 p.m. _____________ 7:45 a.m. _____________
8:30 a.m. _____________ midnight _____________
6:05 p.m. _____________ 9:35 a.m. _____________
1:20 p.m. _____________ 12:30 a.m. _____________
Exercise #2

Convert the following to 12-hour time.

0606 _____________ 2118 ______________
2230 _____________ 1100 ______________
0000 _____________ 0643 ______________
1345 _____________ 2000 ______________
0855 _____________ 1705 ______________
1830 _____________ 0517 ______________
1515 _____________ 0005 ______________
1918 _____________ 1630 ______________
1210 _____________ 2220 ______________

U.S. Tome Zone Exercises:

1. Your flight departs Boston Logan Airport for Los Angeles, CA at 11:40 a.m. EST. The flying time is five hours 40 minutes. What time will you arrive in Los Angeles?

2. In what time zone is Detroit located?

3. If the flying time from Detroit to Chicago is one hour and you leave Detroit at 11:00 a.m., local time, what time will you arrive in Chicago?

4. You are a New York based Flight Attendant with a layover in Seattle. You request a wake-up call from the hotel operator at 6:00 a.m. What time will it be according to your watch set on EST?

5. Your flight departs San Francisco, California for Honolulu, Hawaii at 11:10 a.m. PST. The flying time is five hours and 40 minutes. What time will you arrive in Honolulu?

Answers to Exercises

24-Hour Clock Exercise #1

12-hour times converted to 24-hour times

10:00 p.m. 2200 5:15 a.m. 0515
3:15 a.m. 0315 3:40 p.m. 1540
noon 1200 1:55 a.m. 0155
5:30 p.m. 1730 :30 a.m. 0630
10 a.m. 1010 9: 17 p.m. 2117
7:55 p.m. 1955 8:00 p.m. 2000
2:45 p.m. 1445 7:45 a.m. 0745
8:30 a.m. 0830 midnight 2400 or 0000
6:05 pam. 1805 9:35 a.m. 0935
1:20 p.m. 1320 12:30 a.m. 0030
24-Hour Clock Exercise #2

24-hour times converted to 12-hour times

0606 6:06 a.m. 2118 9:18 p.m.
2230 10:30 p.m. 1100 11:00 a.m.
0000 midnight 0643 6:43 a.m.
1345 1:45 p.m. 2000 8:00 p.m.
0855 8:55 a.m. 1705 5:05 p.m.
1830 6:30 p.m. 0517 5:17 a.m.
1515 3:15 p.m. 0005 12:05 a.m.
1918 7:18 p.m. 1630 4:30 p.m.
1210 12:10 p.m. 2220 10:20 p.m.
U.S. Time Zone Exercise

1. 2:20 p.m.
2. EST (Eastern Time)
3. 11:00 a.m. CST
4. 9:00 a.m.
5. 2:50 p.m. HST

Leave a Reply

Your email address will not be published. Required fields are marked *