Nigerian President Olusegun Obasanjo visits Sokoto Monday, to mark the loss of the spiritual leader of Nigerian Muslims and other prominent victims of the country's latest air crash. 
The preliminary investigation suggests human error might be the cause of Sunday's crash near the Nigerian capital.
At least 99 people died when the passenger jet crashed, shortly after takeoff, on a flight from Abuja to the northern city, Sokoto.
Roland Iyayi, director general of the Nigerian Airspace Management Agency, says the pilot of the Boeing 737 aircraft ignored instructions to delay takeoff because of bad weather.
"At the time of the crash, there were three airlines (aircraft) asking to depart, of which the crashed aircraft was one of them," Iyayi says. "The other two airlines opted to hold due to the advisory from the control tower that the weather was adverse. However, the ADC airline chose to go to a holding point on the runaway, to hold till the weather cleared. At some point during the hold, he called the control tower to indicate that he felt he had a window to go through. He took off, this was about 10:29, local time, in the morning, and he disappeared just after climbing to about one-thousand feet. The next thing we knew from control tower was that there was smoke."
Several people survived the crash.

This is Nigeria's third aviation disaster in a little more than one year. Aviation Minister Babalola Borishade says all ADC planes have been grounded, indefinitely, and the company's license to fly has been lifted.  Borishade says the government may impose sanctions on individuals at ADC, at the end of ongoing investigations.
"We are talking about sanctions. What sanctions can bring the lives of these people back? What sanctions? They lost a plane.  They are going to pay (increased) insurance.  Their reputation is down. And, then, when the accident investigation concludes its business and we know the root cause, of course there are processes for sanctioning people," Borishade says.
Jerome Onipede arrived at the accident scene minutes after the crash.  He
describes what he saw to VOA.
"The plane had broken into pieces. We found out that there were some farmers who were on site," Onipede says. "I saw a lot of Nigerians work with passion, to at least bring out the corpses because they had to cut the plane into pieces, just to make sure they got out the rest of the bodies. Most of the bodies were mutilated. They were beyond recognition."
Among those who died in the crash was Sultan Muhammad Maccido, the spiritual leader of Nigerian Muslims.  The sultan was returning to his Sokoto home with family members, including his son, who served as a Nigerian senator.
Another senator from Sokoto and the state deputy governor were also killed in the crash.
Sokoto journalist Aminu Bello says the ancient town has been in deep mourning since the news of the crash broke.
"Nothing is going on now, since yesterday.  Business activities, everything is at a standstill. I don't expect the market will be opened today. Since yesterday, when they heard the sad news, they closed the market," Bello says.
More than 100 people died, last October, when a Bellview Airlines Boeing 737 crashed near Lagos.  Seven weeks later, 106 people -- most of them school children -- were killed in another crash in Port Harcourt, the oil industry hub in the southeast.
And, last month, 13 senior army officers died when a military aircraft went down in central Benue state.
Despite this disturbing trend, the aviation minister insists air disasters are not peculiar to Nigeria.
"Accidents do occur and nobody is God. The shuttle -- which is the most well-developed aircraft in the world, surrounded by the most experienced air management team -- had a problem. Yes, accidents do occur.  But how do you respond to such accidents? And about a month ago, we did a demonstration here on how to respond to accidents and this has helped us
tremendously today," Borishade says.
The government had promised major improvements in the aviation industry, to enhance safety following previous air mishaps. Sunday's crash could have far-reaching repercussions for local air travel, which has enjoyed a boom in recent years.