Having to call an employer to tell him you must miss a job interview is not a pleasant experience. It sends the signal that you may be an unreliable person. Being polite and calling as soon as you know you will miss the interview are steps you can take to alleviate a bad first impression.
If you are stuck on the side of the road because your fuel pump went out, you blew a tire or you had other car trouble, you will not likely make it to your interview on time. As soon as you can, call the employer and let him know the situation. Speak calmly and confidently on the phone. State the situation without over-dramatising or being profusely apologetic.
If you are faced with a medical emergency involving yourself or your child, you must take care of the situation before you go to a job interview. Whether you have to pick your child up from school because she is ill and no one else is available or you have a car wreck on the way to the interview, your first priority is to get treatment as soon as possible. Once any immediate danger passes, call the employer to explain.
Being there for your family and friends when a loved one dies is more important than a job interview. Call the employer to let him know that you cannot come to the interview because someone close to you has died, and that the date and time of the funeral will not allow you to come. The employer may be willing to reschedule.
Honesty is the best policy when it comes to telling an employer why you missed a job interview. Do not try to cover up that you simply forgot the interview or that you are stuck in traffic because you failed to account for the morning rush. Be sincere in your apology to the employer, and request another interview time. If the employer says no, thank the interviewer for the confidence he showed in you by inviting you to interview and wish him the best. End on a positive note. You may come back to the employer to interview for another position in the future.